Scott Guthrie announced the Atlas project in a recent blog post. The Atlas project aims at considerably simplifying and enriching the client script development experience. It includes but is not limited to AJAX/callbacks and cross-browser client-side declarative binding of elements and behaviors. One of our goals is to leverage the experience of client-side programming that exists inside Microsoft (see Outlook Web Access, MSN Spaces, MSN Virtual Earth, etc.) and give easy access to that technology to developers.
Here are the first press articles on the announcement: