Provide native support in the IDE for MVVM
Something like where VS has a "code mode" for code behind or MVVM or other pattern.
If MVVM is selected then the IDE helps us fall into the pit of MVVM success.
Even better would be a coding mode provider model, so other patterns could be plugged in over time
We got ASP.Net MVC. Now bring us WPF MVVM :-)
Also vote for the Silverlight version of this suggestion http://dotnet.uservoice.com/forums/4325-silverlight-feature-suggestions/suggestions/1420453-it-s-about-time-for-mvvm-to-become-a-part-of-the-s?ref=title
I think RIA Services should be supported in WPF as well, then, the designer should generate strongly-typed view-models per entity.
ViewModel<Customer> etc, so we can handle code without boxing and unboxing over and over (I suggest there should be some extension methods that retrieve the properties by lambda etc.; once you're strongly-typed, everything is hell of a lot easier.
It would be great to have a dynamic behaviour like the one we have with the external resources and templates. I can easily bing visually an external .dll with the pack syntax and render the current style in VS but if I bind a complex ViewModel I still need to run F5. It's not productive when you work on a big project, especially with Prism becuase the compilation time became a bottleneck.