This version is a complete rewrite of the control to use the ASP.NET AJAX Extensions. This version also supports Virtual Earth v4 only.
Note: There are a number of differences between this release and other previous releases of the control. Therefore, there is no recommended upgrade path from previous versions to this one. If you are upgrading, you'll need to rewrite some code.
This release doesn't have a very full set of features; that is actually the reason it is marked as Alpha.
ASP.NET AJAX Extensions v1.0
ASP.NET AJAX Control Toolkit (release 10201 Prod or later)