下载地址：http://www.codeplex.com/aspnet/Release/ProjectReleases.aspx?ReleaseId=18801

This release contains a preview version of the following features (that are also described in our Roadmap document: ASP.NET AJAX Roadmap):
 

• ADO.NET Data Services support
• ASP.NET AJAX Client Templates
• Declarative instantiation of client-side controls and behaviors
• Observable pattern for plain JavaScript objects
• Live Bindings
• Markup Extensions
• DataView and DataSource controls
• Command Bubbling  
• （个人感觉：微软在Ajax框架上对基础架构做的很踏实很实用，但UI上怎么一改常态，没有更多的好东东，如果加上这些则此框架牛上加牛也，呵呵，看好！不像其他UI框架华丽），

官方文档：http://quickstarts.asp.net/previews/ajax/templates/default.aspx