I am a bit late, but because of how busy I have been, I forgot to mention that ASP.NET AJAX has been released. Scott Guthrie has a great post with some great resources about what is new and resources to help you get started.

Links:

http://weblogs.asp.net/scottgu/archive/2007/01/23/asp-net-ajax-1-0-released.aspx
http://weblogs.asp.net/scottgu/archive/2007/01/25/links-to-asp-net-ajax-1-0-resources-and-answers-to-some-common-questions.aspx

Download the Bits:

http://ajax.asp.net/downloads/default.aspx?tabid=47

Remember, have lots of fun with this. I think you will enjoy it.

David