Steven Harding has made available for download his Media Center development book, while the book is not complete (call it a beta) if you interested in Media Center development its well worth a look. There is over 150 pages of detailed Vista Media Center developer information available for free or if you would like a printable version donate via paypal and Steven will send you a watermark free printable copy.
OK - I've put an incomplete version of the book online at the Push-A-Button website - http://push-a-button.com/products/books/index.php
You are welcome to download it and have a read. If you like it or find it valuable, PLEASE consider donating, since it takes quite a bit of time to write up a document like this.
It's 150 pages long and goes into much more detail than the blog here. It covers most of the same topics, but in a slightly different way. I've only started on the "Building a Real Life Application" section.