diff -urN redmine.org/app/controllers/application.rb redmine/app/controllers/application.rb
--- redmine.org/app/controllers/application.rb	2009-09-07 10:13:31.000000000 +0200
+++ redmine/app/controllers/application.rb	2009-09-04 14:55:52.000000000 +0200
@@ -17,6 +17,7 @@
 
 require 'uri'
 require 'cgi'
+require 'icalendar'
 
 class ApplicationController < ActionController::Base
   layout 'base'
@@ -163,6 +164,29 @@
     render :template => "common/feed.atom.rxml", :layout => false, :content_type => 'application/atom+xml'
   end
   
+#EDIT
+def render_ics(items, options={})
+	cal = Icalendar::Calendar.new
+	items.each { |i| 
+		event = Icalendar::Event.new
+		event.dtstart     =  i.start_date
+		event.dtend       =  i.due_date
+		if i.is_a? Issue
+			event.summary     =  i.subject
+		else
+			event.summary     =  "V. " + i.name
+		end
+      
+		if !i.description.nil?
+			event.description = i.description
+		end
+		cal.add_event(event)
+	}
+	@cal_string = cal.to_ical 
+	render :template => "common/calendar.ics.erb", :layout => false , :content_type => Mime::ICS
+end
+  
+  
   def self.accept_key_auth(*actions)
     actions = actions.flatten.map(&:to_s)
     write_inheritable_attribute('accept_key_auth_actions', actions)
diff -urN redmine.org/app/controllers/issues_controller.rb redmine/app/controllers/issues_controller.rb
--- redmine.org/app/controllers/issues_controller.rb	2009-09-07 10:13:31.000000000 +0200
+++ redmine/app/controllers/issues_controller.rb	2009-09-04 14:50:42.000000000 +0200
@@ -366,6 +366,10 @@
     retrieve_query
     if @query.valid?
       events = []
+	  #EDIT
+	  if (request.format == Mime::ICS)
+	        @calendar.startdt = @project.created_on.to_s(:db)
+	  end
       events += Issue.find(:all, 
                            :include => [:tracker, :status, :assigned_to, :priority, :project], 
                            :conditions => ["(#{@query.statement}) AND ((start_date BETWEEN ? AND ?) OR (due_date BETWEEN ? AND ?))", @calendar.startdt, @calendar.enddt, @calendar.startdt, @calendar.enddt]
@@ -376,7 +380,12 @@
       @calendar.events = events
     end
     
-    render :layout => false if request.xhr?
+    #render :layout => false if request.xhr?
+	#EDIT
+	respond_to do |format|
+		format.html { render :layout => false if request.xhr? }
+		format.ics  { render_ics(events) }
+	end  
   end
   
   def context_menu
diff -urN redmine.org/app/views/common/calendar.ics.erb redmine/app/views/common/calendar.ics.erb
--- redmine.org/app/views/common/calendar.ics.erb	1970-01-01 01:00:00.000000000 +0100
+++ redmine/app/views/common/calendar.ics.erb	2009-09-04 14:59:00.000000000 +0200
@@ -0,0 +1 @@
+<%= @cal_string %>
diff -urN redmine.org/lib/redmine/helpers/calendar.rb redmine/lib/redmine/helpers/calendar.rb
--- redmine.org/lib/redmine/helpers/calendar.rb	2009-09-07 10:13:29.000000000 +0200
+++ redmine/lib/redmine/helpers/calendar.rb	2009-09-04 14:39:59.000000000 +0200
@@ -45,6 +45,10 @@
         end
       end
       
+	  def startdt=(dt)
+		@startdt = dt
+	  end
+	  
       # Sets calendar events
       def events=(events)
         @events = events