We just posted a new version of the Composite Application Guidance for WPF and Silverlight (Prism 2.1) to run on Silverlight 3.0.

This minor update includes:

• Projects refreshed to target Silverlight 3.0
• Changes in DelegateCommand and CompositeCommand to no longer hold on to CanExecuteChange handlers.
• The TabRegionControlAdapter was updated to set the context for the Header item to retain the same behavior as Prism 2.0.

You can download the bits from here and you find more details about the changes on the MSDN page.

If you are interested in a customer that is using Prism, check out my recent blog post.