As of today, Microsoft has officially released ASP.NET 2.0 AJAX Extensions to the web. This will be available under the Microsoft Reference License (Ms-RL).
ASP.NET AJAX 1.0 is a free framework for creating AJAX-enabled applications. Using the ASP.NET 2.0 AJAX Extensions you'll be able to create interfaces and components that take advantage of the AJAX technology. All major browsers should support these interfaces and components.
You can download ASP.NET AJAX 1.0 from http://go.microsoft.com/fwlink/?LinkID=77296.
For those that are adventurous, you can also download the ASP.NET AJAX Futures Community Technology Preview (CTP). This contains early releases of new AJAX features that Microsoft is working on.
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