This is just about the best thing I've heard in the last couple of years. Scott Guthrie showed a prototype of an MVC framework on the MVP Summit (ship it!).
This framework can be compared with Ruby on Rails and MonoRail. A handler factory that determines from the URL which controller to instantiate and load. From the description, it sounds very cool and I hope that Microsoft will do the right thing: testability and maintainability right out-of-the-box. We can only hope that Microsoft will pick up some of the ideas behind the existing open-source frameworks.
It has been a long time since I've been this excited about some new stuff coming from Microsoft. I would love to get my hands on some bits!