Num Lock must be on. Use "4" to go left, "6" to go right. Space bar starts a game.
Here is my evaluation of Silverlight. Naturally, it is in the form of a JetLag clone.
It was really easy to get up and going, with the most major setback being the question of how to get a simple frame loop going. Once that was solved (and it is a bit of a hack, imo), JetLag wasn't too far away.
The VS Template was not really helpful. Sure, it allowed me to create the boilerplate code for a project, but in the end, I'm no better off than I was working in NotePad++. Besides it is typically only a matter of time before I have my own homebrewed boilerplate anyway.
Documentation was spotty, but this is pre-release, so I don't expect much. I was able to glean enough from the example code to know what I needed to know.
My main complaint was that the application exists in a bunch of .js and .xaml files, which are just sitting there on the webserver in plaintext, so anyone who knows how can inspect my code and take what they want from it, and that may not be what you are looking for in a platform for online applications.
This lies somewhere between Flash and Yahoo! Widgets for me. I'm going to wait and watch and see.