Brian Noyes from IDesign is one of the great folks helping us in the design and development of Prism. Brian brings a breadth of experience with WPF, and has worked significantly with CAB. He also was the author of the click-once integration pieces in SCSF. Recently he put together a great post speaking on the work we are doing. He talks about composite applications, what Prism is, and also the state of the project.
I've been meaning to do a similar post, but thanks to Brian I am off the hook. :-)
Check it out here