The WPF team at Microsoft has released a toolkit (version 0.1) that addresses developing UIs with the M-V-VM pattern.
It's definitely a first-pass (e.g. no VB.NET support), but they are looking for feedback on this effort. There is also a bit of confusion as to how this compares to the Silverlight development pattern in RIA Services. See this StackOverflow discussion.
The toolkit includes:
- A Visual Studio 2008 template (Visual C# Express 2008 also supported)
- General introduction to M-V-VM
- Walkthrough using the VS template
- A complete WPF application demonstrating the M-V-VM pattern
Here's a post about ViewModel and how it enhances the UI's testability.
Check it out here: WPF Model-View-ViewModel Toolkit