The Patterns and Practices team @ Microsoft have been busy working on helping answer the question – how do I maximize my skills in XAML and .NET development to build for both Silverlight and WPF.
The result: Prism 2.0 has just been released to the wild. You can find it on CodePlex here.
The focus is on Line-of-Business or Enterprise applications, and these types of applications typically feature multiple screens, rich, flexible user interaction and data visualization, and role-determined behavior. They are built to last and built for change. This means that the application's expected lifetime is measured in years and that it will change in response to new, unforeseen requirements. This application may start small and over time evolve into a composite client—composite applications use loosely coupled, independently evolvable pieces that work together in the overall application.
The release includes the Composite Application Library; a Reference Implementation application based on a Stock Trading scenario, built in both WPF and Silverlight; some Quick Start and How-To Applications as well as full documentation on everything you need to know about UI patterns and client architectures, but were afraid to ask.