The formerly known Atlas is now ASP.NET AJAX and was released as v1.0 Beta last week. You can download the free framework here. The accompanying site has quite a few “How Do I” videos that show off the framework and guide you through using some of the features. See the video list here. I watched the 18 minute video entitled Developing ASP.NET 2.0 Applications using AJAX and was impressed with the simplicity of developing with ASP.NET AJAX.