Today Microsoft released final version of Microsoft ASP.NET AJAX framework (former ATLAS).
You can download ASP.NET ajax final release components below:
With ASP.NET AJAX, developers can quickly create pages with rich, responsive UI and more efficient client-server communication by simply adding a few server controls to their pages. This new Web development technology from Microsoft integrates cross-browser client script libraries with the ASP.NET 2.0 development framework. ASP.NET AJAX provides developers building client-based Web experiences with a familiar development process and programming model that they already know from using server-side ASP.NET development. Because ASP.NET AJAX is integrated with ASP.NET, developers have full access to the built-in ASP.NET 2.0 application services and the entire .NET Framework.