After a year full of CTP releases Microsoft ASP.NET AJAX is in beta! Read the announcement and the details on Scott Guthrie's blog.
On the http://ajax.asp.net/ there's a lot of information available on this first beta. Especially the migration guide will be very helpful when transitioning applications built with the earlier "Atlas" CTPs to this first beta. Check also the detailed whitepaper "Changes between the ASP.NET AJAX (“Atlas”) CTP and the v1.0 Beta Release" (Microsoft Word, PDF Document) that describes the changes and how to migrate your applications successfully.
When browsing through these documents you will notice that quite some features changed from the CTP to the 1.0 release. Take a look at the feature matrix below that I copied from the changes document.
ASP.NET AJAX 1.0
ASP.NET AJAX CTP
1 - UpdateProgres will move from the ASP.NET AJAX CTP to ASP.NET AJAX 1.0 in the Release Candidate.
ASP.NET AJAX has been factored into two separate downloads in reparation for the RTM release:
The features that didn't made it to the core release will be made available later on through value-add CTP releases.
All the above means that we're on track for some more announcements at TechEd: Developers. All ASP.NET AJAX sessions are 100% live on the TechEd web site, including scheduling information.