SharePoint Dragons

You can’t access the HttpContext within an ItemAdded event receiver, which makes sense, as there is none anymore. If you want to access the querystring in it, you can retrieve it in the ItemAdding event and pass it to the ItemAdded event via the HttpRuntime cache: http://social.technet.microsoft.com/Forums/en-US/sharepoint2010general/thread/421a6a2b-22ce-4aa8-8d14-944493eddc6c