Wow, the ASP.NET MVC team just keeps getting it right!
I am truly shocked that Microsoft is going to take advantage of a well-known, well-tested open source framework instead of trying to (poorly) invent their own... (cough... ASP.NET Ajax)
Scott Gu - jQuery and Microsoft :
http://weblogs.asp.net/scottgu/archive/2008/09/28/jquery-and-microsoft.aspx