Atlas with any othe name is: Microsoft AJAX Library
For some of you who are still calling Microsoft AJAX, "Atlas" the name has changed.
for further information you can also look at the ASP.NET AJAX Control Toolkit project page on CodePlex. CodePlex is Microsoft's community development web site. You can use CodePlex to create new projects to share with your fellow developers around the world, join others who have already started their projects, or use the applications on this site and provide feedback.