From Scott Guthrie's Blog:
Today I am very pleased to announce the first official Beta release of Microsoft ASP.NET AJAX v1.0. You can download it now from the http://ajax.asp.net site. Available on the site are three download options:
1) The ASP.NET AJAX v1.0 “Core” download. This redist contains the features that will be fully supported by Microsoft Product Support, and which will have a standard 10 year Microsoft support license (24 hours a day, 7 days a week, 365 days a year). The download includes support for the core AJAX type-system, networking stack, component model, extender base classes, and the server-side functionality to integrate within ASP.NET (including the super-popular ScriptManager, UpdatePanel, and Timer controls).
2) The ASP.NET AJAX “Value-Add” CTP download. This redist contains the additional higher-level features that were in previous CTPs of “Atlas,” but which won’t be in the fully-supported 1.0 “core” redist. These features will continue to be community supported as we refine them further and incorporate more feedback. Over time we’ll continue to move features into the “core” download as we finalize features in this value-add package more.
3) The ASP.NET AJAX Control Toolkit. This project contains 28 free, really cool, AJAX-enabled controls that are built on top of the ASP.NET AJAX 1.0 “Core” download. The project is collaborative shared source and built by a combination of Microsoft and non-Microsoft developers, and you can join the community or just download it on CodePlex today.