Don't get me wrong: I beleive WPF is the right idea but it's way to expensive to use to develop most business applications.

The biggest shame is how Microsoft decided to reinvent the wheel when all it needed to do was brush up DirectUI, which would have provided next-generation UIs to Native applications, as well as that "Proto-WPF" that's been present in Windows Media Center and the Zune desktop software for some time now.

If I were in Microsoft's position, I would recreate Windows' windowing engine as a compositing system with inherent 3D support with a similar architecture to WPF, and then provide CLR bindings on-top. It worked for WinForms.