Or maybe everything is in a cycle...

  1. Develop XPS, awesome fixed format document and print stream format
  2. Develop Silverlight, fantastic cross-platform, cross-browser plug-in for richer media and interactive applications
  3. Write book introducing Silverlight 2
  4. Implement some XPS support using Silverlight
  5. Make first three chapters of book available for reading online as an XPS document hosted in a Silverlight viewer

Enjoy.