As you know, MS announced that jQuery is a built-in library in VS 2008 SP1 for ASP.NET Developers.
I recommend for all developers, to see the series of jQuery Library videos from its own creator : John Resig and his team, this series of videos help you to understand the jQuery library features,jQuery UI and other important notes for advanced developers.
I enjoyed watching these series, and i suggest all of you to understand and start using jQuery library in your .NET Projects and solutions.
After you finish this series, i like to share with you these posts for integrating ASP.NET with jQuery library:
1) ASP.NET with jQuery: Scott hanselman:
2) ASP.NET with jQuery:
Hope this helps.