Scott Guthrie has a great blog entry on several platform enhancements, code-name Atlas, that will address AJAX-style programming. At the same time, Charles Fitzgerald presented the Atlas technologies.

Microsoft will release a technology preview of Atlas at the PDC, which will be held in Los Angeles. 

This is very nice - it makes complete sense to have AJAX-style development facilities built in the development platform. You should not be required to write and debug complex AJAX code.