A while back, I was Dev Lead on the Smart Client Software Factory (SCSF) when we added the ability to host WPF controls in a Composite Application Block (CAB) application. Since then, the thinking in the WPF space has changed a bit, and p&p decided that offering guidance on full WPF applications was a good idea. Blaine, Francis, Bob, and Glenn have worked with a great team to create guidance for building composite applications using WPF. This guidance was started from a clean slate, as there are enough differences between Windows Forms and WPF (as we learned doing SCSF) to cause challenges. The result is the Composite Application Guidance for WPF June 2008, which recently shipped (formerly code-named Prism). This guidance is simple, easy to consume, can be used piecemeal, and should not have the steep learning curve that CAB and SCSF have. You can learn more at the Prism CodePlex Community Site, or at any of the places below.
Check out Francis's post, SHIPPED!!! Composite Application Guidance for WPF June 2008, for details and where to get it.
Or take a look at Glenn's post on the subject: Composite Application Guidance is Live
And here are a few other posts about what they have been up to, by person in chronological order:
I know I am looking forward to using this guidance when I get a chance to work with WPF more seriously.