Atlas Beta (or Microsoft ASP.NET AJAX v1.0 Beta)
Microsoft ASP.NET AJAX v1.0 Beta (code-named “Atlas”) is now available to download - it provides a preview of the fully-supported version of ASP.NET AJAX scheduled for release by the end of this year.
Frank Arrigo has some useful links relating to this release.
Update: Microsoft's Scott Guthrie a posted a lot more detail on this beta release.