Index: application_controller.rb
===================================================================
--- application_controller.rb	(revision 15949)
+++ application_controller.rb	(working copy)
@@ -487,6 +487,13 @@
       format.html {
         render :template => 'common/error', :layout => use_layout, :status => @status
       }
+      format.js {
+        render :status => @status, :text => "alert(\"#{@status}: #{@message}\")"
+      }
+      format.api {
+        @error_messages = [@message]
+        render :template => 'common/error_messages.api', :status => @status
+      }
       format.any { head @status }
     end
   end