I was at the Project SILK (http://silk.codeplex.com/) workshop at Microsoft in February (http://silk.codeplex.com/wikipage?title=25%20Feb%202011%20Web%20Workshop) and they introduced an awesome JS framework called Knockout JS for doing MVVM with java script on the front end.
The cool thing about it? You get some sweet client side model binding very similar to WPF and Silverlight (model binding is awesome in those).
See the presentation from MIX11.
http://channel9.msdn.com/Events/MIX/MIX11/FRM08
I think this would be great to incorporate into the core site moving forward (if you don't I will in my version).
Thoughts?