Checkout these videos of the Silverlight mobile demos that were shown at the MIX08 keynote just this last week.
MIXr
Mobile Social Networking with Silverlight 2
WeatherBug
Weather Beyond the Browser with WeatherBug
Read the complete post at http://blogs.msdn.com/lokeuei/archive/2008/03/08/silverlight-mobile-at-mix08.aspx