Laurence Moroney just published a blog post in which he adapted David Anson's XPS Viewer for Silverlight sample to allow reading the first 3 chapters of his Silverlight 2 book using a SIlverlight/XPS experience.
(you can check the full screen version here)
While of course this may be improved, it is a further demonstration of how easy it is to integrate these technologies!!! Kudos to David and Laurence to make this happen…
I am looking forward to see further refinements and other applications of this code!