diff --git a/app/controllers/auto_completes_controller.rb b/app/controllers/auto_completes_controller.rb
index 27226ea8..f1fe99c7 100644
--- a/app/controllers/auto_completes_controller.rb
+++ b/app/controllers/auto_completes_controller.rb
@@ -48,8 +48,14 @@ class AutoCompletesController < ApplicationController
     end
 
     @removed_users ||= []
+
+    if params[:include_groups]
+      user_finder = Principal
+    else
+      user_finder = User
+    end
     
-    @users = User.active.like(params[:q]).find(:all, :limit => 100) - @removed_users
+    @users = user_finder.active.like(params[:q]).find(:all, :limit => 100) - @removed_users
     render :layout => false
   end
   
diff --git a/app/controllers/watchers_controller.rb b/app/controllers/watchers_controller.rb
index 5d5d2d50..2325634a 100644
--- a/app/controllers/watchers_controller.rb
+++ b/app/controllers/watchers_controller.rb
@@ -53,7 +53,7 @@ class WatchersController < ApplicationController
   end
 
   def destroy
-    @watched.set_watcher(User.find(params[:user_id]), false) if request.post?
+    @watched.set_watcher(Principal.find(params[:user_id]), false) if request.post?
     respond_to do |format|
       format.html { redirect_to :back }
       format.js do
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index f4396b56..dde5943a 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -912,6 +912,12 @@ module ApplicationHelper
   # +user+ can be a User or a string that will be scanned for an email address (eg. 'joe <joe@foo.bar>')
   def avatar(user, options = { })
     if Setting.gravatar_enabled?
+      if user.is_a?(Group)
+        size = options[:size] || 50
+        size = "#{size}x#{size}" # image_tag uses WxH
+        options[:class] ||= 'gravatar'
+        return image_tag("group.png", options.merge(:size => size))
+      end
       options.merge!({:ssl => (defined?(request) && request.ssl?), :default => Setting.gravatar_default})
       email = nil
       if user.respond_to?(:mail)
diff --git a/app/models/group.rb b/app/models/group.rb
index 2e7d3526..2b29a8b9 100644
--- a/app/models/group.rb
+++ b/app/models/group.rb
@@ -22,6 +22,11 @@ class Group < Principal
   validates_uniqueness_of :lastname, :case_sensitive => false
   validates_length_of :lastname, :maximum => 30
 
+  # Returns an array of all of the email addresses of the group's users
+  def mails
+    users.collect(&:mail)
+  end
+  
   def to_s
     lastname.to_s
   end
diff --git a/app/models/principal.rb b/app/models/principal.rb
index 3c390bb2..ada2cfaa 100644
--- a/app/models/principal.rb
+++ b/app/models/principal.rb
@@ -48,6 +48,82 @@ class Principal < ActiveRecord::Base
     end
   end
 
+  def active?
+    true
+  end
+
+  def logged?
+    true # TODO: should all principals default to logged or not?
+  end
+
+  # Return true if the user is allowed to do the specified action on a specific context
+  # Action can be:
+  # * a parameter-like Hash (eg. :controller => 'projects', :action => 'edit')
+  # * a permission Symbol (eg. :edit_project)
+  # Context can be:
+  # * a project : returns true if user is allowed to do the specified action on this project
+  # * a group of projects : returns true if user is allowed on every project
+  # * nil with options[:global] set : check if user has at least one role allowed for this action,
+  #   or falls back to Non Member / Anonymous permissions depending if the user is logged
+  def allowed_to?(action, context, options={})
+    if context && context.is_a?(Project)
+      # No action allowed on archived projects
+      return false unless context.active?
+      # No action allowed on disabled modules
+      return false unless context.allows_to?(action)
+      # Admin users are authorized for anything else
+      return true if admin?
+
+      roles = roles_for_project(context)
+      return false unless roles
+      roles.detect {|role| (context.is_public? || role.member?) && role.allowed_to?(action)}
+
+    elsif context && context.is_a?(Array)
+      # Authorize if user is authorized on every element of the array
+      context.map do |project|
+        allowed_to?(action,project,options)
+      end.inject do |memo,allowed|
+        memo && allowed
+      end
+    elsif options[:global]
+      # Admin users are always authorized
+      return true if admin?
+
+      # authorize if user has at least one role that has this permission
+      roles = memberships.collect {|m| m.roles}.flatten.uniq
+      roles.detect {|r| r.allowed_to?(action)} || (self.logged? ? Role.non_member.allowed_to?(action) : Role.anonymous.allowed_to?(action))
+    else
+      false
+    end
+  end
+
+  # Is the user allowed to do the specified action on any project?
+  # See allowed_to? for the actions and valid options.
+  def allowed_to_globally?(action, options)
+    allowed_to?(action, nil, options.reverse_merge(:global => true))
+  end
+
+  # Return user's roles for project
+  def roles_for_project(project)
+    roles = []
+    # No role on archived projects
+    return roles unless project && project.active?
+    if logged?
+      # Find project membership
+      membership = memberships.detect {|m| m.project_id == project.id}
+      if membership
+        roles = membership.roles
+      else
+        @role_non_member ||= Role.non_member
+        roles << @role_non_member
+      end
+    else
+      @role_anonymous ||= Role.anonymous
+      roles << @role_anonymous
+    end
+    roles
+  end
+  
   protected
 
   # Make sure we don't try to insert NULL values (see #4632)
diff --git a/app/models/user.rb b/app/models/user.rb
index 49a9bf4f..63296e8b 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -345,27 +345,6 @@ class User < Principal
     !logged?
   end
 
-  # Return user's roles for project
-  def roles_for_project(project)
-    roles = []
-    # No role on archived projects
-    return roles unless project && project.active?
-    if logged?
-      # Find project membership
-      membership = memberships.detect {|m| m.project_id == project.id}
-      if membership
-        roles = membership.roles
-      else
-        @role_non_member ||= Role.non_member
-        roles << @role_non_member
-      end
-    else
-      @role_anonymous ||= Role.anonymous
-      roles << @role_anonymous
-    end
-    roles
-  end
-
   # Return true if the user is a member of project
   def member_of?(project)
     !roles_for_project(project).detect {|role| role.member?}.nil?
@@ -388,53 +367,6 @@ class User < Principal
     @projects_by_role
   end
 
-  # Return true if the user is allowed to do the specified action on a specific context
-  # Action can be:
-  # * a parameter-like Hash (eg. :controller => 'projects', :action => 'edit')
-  # * a permission Symbol (eg. :edit_project)
-  # Context can be:
-  # * a project : returns true if user is allowed to do the specified action on this project
-  # * a group of projects : returns true if user is allowed on every project
-  # * nil with options[:global] set : check if user has at least one role allowed for this action,
-  #   or falls back to Non Member / Anonymous permissions depending if the user is logged
-  def allowed_to?(action, context, options={})
-    if context && context.is_a?(Project)
-      # No action allowed on archived projects
-      return false unless context.active?
-      # No action allowed on disabled modules
-      return false unless context.allows_to?(action)
-      # Admin users are authorized for anything else
-      return true if admin?
-
-      roles = roles_for_project(context)
-      return false unless roles
-      roles.detect {|role| (context.is_public? || role.member?) && role.allowed_to?(action)}
-
-    elsif context && context.is_a?(Array)
-      # Authorize if user is authorized on every element of the array
-      context.map do |project|
-        allowed_to?(action,project,options)
-      end.inject do |memo,allowed|
-        memo && allowed
-      end
-    elsif options[:global]
-      # Admin users are always authorized
-      return true if admin?
-
-      # authorize if user has at least one role that has this permission
-      roles = memberships.collect {|m| m.roles}.flatten.uniq
-      roles.detect {|r| r.allowed_to?(action)} || (self.logged? ? Role.non_member.allowed_to?(action) : Role.anonymous.allowed_to?(action))
-    else
-      false
-    end
-  end
-
-  # Is the user allowed to do the specified action on any project?
-  # See allowed_to? for the actions and valid options.
-  def allowed_to_globally?(action, options)
-    allowed_to?(action, nil, options.reverse_merge(:global => true))
-  end
-
   safe_attributes 'login',
     'firstname',
     'lastname',
diff --git a/app/models/watcher.rb b/app/models/watcher.rb
index bc1bed6b..aa0fc92a 100644
--- a/app/models/watcher.rb
+++ b/app/models/watcher.rb
@@ -14,8 +14,8 @@
 
 class Watcher < ActiveRecord::Base
   belongs_to :watchable, :polymorphic => true
-  belongs_to :user
-
+  belongs_to :user, :class_name => 'Principal', :foreign_key => 'user_id'
+  
   validates_presence_of :user
   validates_uniqueness_of :user_id, :scope => [:watchable_type, :watchable_id]
 
diff --git a/app/views/watchers/_watchers.rhtml b/app/views/watchers/_watchers.rhtml
index 741366cd..00b4954c 100644
--- a/app/views/watchers/_watchers.rhtml
+++ b/app/views/watchers/_watchers.rhtml
@@ -12,12 +12,12 @@
          	                    :object_id => watched},
        	             :method => :post,
       	             :html => {:id => 'new-watcher-form', :style => 'display:none;'}) do |f| %>
-    <% users = User.active.find(:all, :limit => 25) - watched.watcher_users %>
+    <% users = Principal.active.find(:all, :limit => 25) - watched.watcher_users %>
 		<p><%= label_tag "user_search", l(:label_user_search) %><%= text_field_tag 'user_search', nil, :style => "width:98%;" %></p>
 		<%= observe_field(:user_search,
                  :frequency => 0.5,
                  :update => :users,
-                 :url => auto_complete_users_path(:remove_watchers => watched.id, :klass => watched.class),
+                 :url => auto_complete_users_path(:remove_watchers => watched.id, :klass => watched.class, :include_groups => true),
                  :with => 'q')
                   %>
 		
diff --git a/test/functional/auto_completes_controller_test.rb b/test/functional/auto_completes_controller_test.rb
index 4ee6482d..5881862d 100644
--- a/test/functional/auto_completes_controller_test.rb
+++ b/test/functional/auto_completes_controller_test.rb
@@ -92,6 +92,20 @@ class AutoCompletesControllerTest < ActionController::TestCase
       end
     end
 
+    context "including groups" do
+      setup do
+        @group = Group.generate(:lastname => 'Complete Group').reload
+        get :users, :q => 'complete', :include_groups => true
+      end
+      
+      should_respond_with :success
+      
+      should "include matching groups" do
+        assert_select "input[type=checkbox][value=?]", @group.id
+      end
+
+    end
+
     context "restrict by removing group members" do
       setup do
         @group = Group.first
diff --git a/test/functional/watchers_controller_test.rb b/test/functional/watchers_controller_test.rb
index 858e807e..ad839bac 100644
--- a/test/functional/watchers_controller_test.rb
+++ b/test/functional/watchers_controller_test.rb
@@ -132,6 +132,21 @@ class WatchersControllerTest < ActionController::TestCase
     assert Issue.find(2).watched_by?(User.find(7))
   end
 
+  context "POST :new" do
+    should "add groups" do
+      @group = Group.generate!.reload
+      Member.generate!(:project => Project.find(1), :roles => [Role.find(1)], :principal => @group)
+
+      @request.session[:user_id] = 2
+      assert_difference('Watcher.count') do
+        xhr :post, :new, :object_type => 'issue', :object_id => '2', :user_ids => [@group.id.to_s]
+        assert_response :success
+        assert_select_rjs :replace_html, 'watchers'
+      end
+      assert Issue.find(2).watched_by?(@group)
+    end
+  end
+
   def test_remove_watcher
     @request.session[:user_id] = 2
     assert_difference('Watcher.count', -1) do
@@ -141,4 +156,23 @@ class WatchersControllerTest < ActionController::TestCase
     end
     assert !Issue.find(2).watched_by?(User.find(3))
   end
+
+  context "POST :destroy" do
+    should "remove a group" do
+      @group = Group.generate!.reload
+      Member.generate!(:project => Project.find(1), :roles => [Role.find(1)], :principal => @group)
+      assert Issue.find(2).add_watcher(@group)
+      assert Issue.find(2).watched_by?(@group)
+
+      @request.session[:user_id] = 2
+      assert_difference('Watcher.count', -1) do
+        xhr :post, :destroy, :object_type => 'issue', :object_id => '2', :user_id => @group.id.to_s
+        assert_response :success
+        assert_select_rjs :replace_html, 'watchers'
+      end
+      assert !Issue.find(2).watched_by?(@group)
+    end
+    
+  end
+  
 end
diff --git a/test/unit/watcher_test.rb b/test/unit/watcher_test.rb
index c850849e..7ac1bd58 100644
--- a/test/unit/watcher_test.rb
+++ b/test/unit/watcher_test.rb
@@ -14,11 +14,7 @@
 require File.expand_path('../../test_helper', __FILE__)
 
 class WatcherTest < ActiveSupport::TestCase
-  fixtures :projects, :users, :members, :member_roles, :roles, :enabled_modules,
-           :issues,
-           :boards, :messages,
-           :wikis, :wiki_pages,
-           :watchers
+  fixtures :all
 
   def setup
     @user = User.find(1)
@@ -125,4 +121,34 @@ class WatcherTest < ActiveSupport::TestCase
     assert Issue.find(1).watched_by?(user)
     assert !Issue.find(4).watched_by?(user)
   end
+
+  context "group watch" do
+    setup do
+      @group = Group.generate!
+      Member.generate!(:project => Project.find(1), :roles => [Role.find(1)], :principal => @group)
+      @group.users << @user = User.find(1)
+      @group.users << @user2 = User.find(2)
+    end
+    
+    should "be valid" do
+      assert @issue.add_watcher(@group)
+      @issue.reload
+      assert @issue.watchers.detect { |w| w.user == @group }
+    end
+    
+    should "add all group members to recipients" do
+      @issue.watchers.delete_all
+      @issue.reload
+    
+      assert @issue.watcher_recipients.empty?
+      assert @issue.add_watcher(@group)
+
+      @user.save    
+      @issue.reload
+      assert @issue.watcher_recipients.include?(@user.mail)
+      assert @issue.watcher_recipients.include?(@user2.mail)
+
+    end
+    
+  end
 end
diff --git a/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb b/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb
index 2b158383..9d99d2b7 100644
--- a/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb
+++ b/vendor/plugins/acts_as_watchable/lib/acts_as_watchable.rb
@@ -42,7 +42,7 @@ module Redmine
         
         # Removes user from the watchers list
         def remove_watcher(user)
-          return nil unless user && user.is_a?(User)
+          return nil unless user && user.is_a?(Principal)
           Watcher.delete_all "watchable_type = '#{self.class}' AND watchable_id = #{self.id} AND user_id = #{user.id}"
         end
         
@@ -64,7 +64,14 @@ module Redmine
           if respond_to?(:visible?)
             notified.reject! {|user| !visible?(user)}
           end
-          notified.collect(&:mail).compact
+
+          notified.collect {|w|
+            if w.respond_to?(:mail) && w.mail.present? # Single mail
+              w.mail
+            elsif w.respond_to?(:mails) && w.mails.present? # Multiple mail
+              w.mails
+            end
+          }.flatten.compact
         end
 
         module ClassMethods; end