You can listen to the podcast from Hanselminutes.com. Podcast 37 is an interview with Scott Guthrie.
Also Dino Esposito was busy writing about/teaching ASP.NET AJAX. This resulted in an upcoming book called Introducing ASP.NET 2.0 AJAX Extensions. Best of all, you can download a free chapter of it here.
The TOC of the upcoming book: Building Blocks of Ajax-style Web Applications Building Blocks of the Atlas Application Framework Updatable Page Fragments Atlas Control Toolbox & Behaviors The Atlas Client Library Web Services Client-side Data Binding Atlas Gadgets
I can only hope that the final book will cover the updated Microsoft AJAX bits since last week the Beta 1 was released and I already saw on the ASP.NET forums, where I'm a moderator and top 10 poster, that a lot of threads are added with questions/problems about the new bits as there seems to be a lot of changes since the CTP releases.