The Atlanta Code Camp 2007 (http://www.atlantacodecamp.com) was another successful CodeCamp event.
I presented a session on creating a custom extender with ASP.NET AJAX RC. If you were present in Montgomery, you'll find the download from the Atlanta Code Camp useful, as it has been revised for RC (I used Beta 2 during the Montgomery CodeCamp).
The download (zip file containing demo script and code) is available
here.