2007-09-20 release of the AJAX Control Toolkit has a number of bug fixes identified as important by the community in Calendar, PopupBehavior, AutoComplete, Accordion, ConfirmButton, ModalPopup, MaskedEdit and Slider.
AjaxControlToolkit.zip is the full release package with complete source code to all controls, the test framework, VSI, and more.
AjaxControlToolkit-NoSource.zip contains only the sample web site and VSI and is for people who don't need or want the source code for the controls.
If you would like to try the Toolkit out on .NET Framework 3.5 Beta 2 and Visual Studio 2008 Beta 2 then you can download the AjaxControlToolkit-Framework3.5.zip or the AjaxControlToolkit-Framework3.5-NoSource.zip.
Please see the sample website release notes
for more details.