These guys are awesome. I can't imagine how a complex project like SilverLight could get implemented over Mono in 21 days!! Miguel has this great piece on Implementing Moonlight, which he posted from an airplane en-route to Paris to show the first MoonLight demo! All I can say is ..... WOW!
The post is a "must-read" if you like Mono.
All this is good news for Linux. It means yet another breed of Windows Applications will run on Linux. More compatibility is always better. Earlier, Microsoft had released SilverLight betas only for Windows and the Mac.