Microsoft has published a marketing site for Windows Mobile 6.1, and I'm glad they used Silverlight to create it.
Check it out:
Windows Mobile 6.1 – New Windows Mobile Software for Pocket PC and Smartphone
* imageInstant messaging-like texting
* Improved Internet browsing
* Simpler e-mail and Bluetooth setup
* New Home screen interface
* New Getting Started Center
* Security enhancements
* Easier Wi-Fi connection
* More personal choice
Source: DevHawk - Morning Coffee 160