"Atlas" is a free framework for building a new generation of richer, more interactive, highly personalized standards based Web applications.
Best place to look for Atlas is http://atlas.asp.net and you can download the atlas tool kit, documentations and sample applications from http://atlas.asp.net/default.aspx?tabid=47&subtabid=471
Here are the additional resource links for ATLAS.
MSDN Blogs on ATLAS - http://blogs.msdn.com/federaldev/archive/category/12871.aspx
Jay Kimble wrote many artcles on ATLAS like Atlas: Starting to grasp control development... and How to Add Atlas to an existing site which has a nice walkthrough of the configuration steps you'll need to go through for an existing ASP.NET 2.0 app before you can start dropping Atlas controls on your pages.