Following the recent release of Visual Studio 2008, I scribed a new tutorial on ASP.NET AJAX Custom Controls using the new IDE. I originally estimated two weeks for the project, but in order to put in everything I thought needed to be said about writing AJAX-enabled .NET controls, the effort took over six weeks. Should you have any inclination to see it, you can find it here at www.codeproject.com.
The tutorial is built around the session timeout monitor I originally described at the Imaginative Universal: http://www.imaginativeuniversal.com/SessionExpiredMonitorWithASPNETAJAX.aspx. Since the code for the tutorial is intended primarily to be instructive, I still plan to write one more revision of the session timeout control, in order to streamline the functionality and try to incorporate the modal popup behavior from the AJAX Control Toolkit, which I will publish in the pages of this blog.