You just have to see this to believe it. This has been a strangely popular Internet play toy, and many videos have been recorded. Here's more from their site...
Boy grabs sled. Boy rides sled. A simple concept yields endless fun and the latest Internet Phenomenon is born! In Line Rider the player draws their own landscape with a simple pencil tool creating as many ramps, hills, and jumps as they can imagine. Then they send a virtual sledder careening down the course until he wipes out. The possibilities in Line Rider are only limited by the player's imagination. Play Line Rider™ Now!
There are hundreds of LineRider videos on YouTube. Now, McDonald's is involved with a contest (see an interesting video here).
Hopefully, you've heard that NBC is showing the Olympic events, using Silverlight. They have lots of video to show, and will stream live events as well. They have an interface that allows you to split up the Olympics in several ways.
With Silverlight Mobile coming down the path, some customers are building early prototypes. One of my DPE teammates in the west, Sam Chenaur, has posted about working with John L. Scott. They have a video of Sam talking to through the application, as well as showing it off on the phone. It uses Virtual Earth too. Here's the interview: Silverlight Mobile with John L Scott Real Estate