The final part from Andrea Boschin's article series on Windows 8 Metro is already published at SilverlightShow, check it out:
From the author:
In the previous number I've introduced push notifications in Windows 8, talking about architectural topics to understand the way this feature works, and about the authentication phase where the client and the cloud service both authenticate themselves to the WNS, to establish a working relation between the actors. Now that the service has been created and the client is connected, the time has come to send out first notification. In this article I will cover, from the simpler to the most complex, notifications that are automatically handled by the client runtime and become badge, tile and toasts.
NOTE: Now that this series is finished, we'll soon convert and release the second part of the Windows 8 Metro ebook (PDF, Word, MOBI & EPUB formats). Part 1, including the first 7 chapters from the series, is available on SilverlightShow Ebook Shelf.