Miguel de Icaza has unveiled "Moonlight," an implementation of Silverlight on Linux by way of Mono. The project was done as a 21-day sprint and while just a prototype, it makes Microsoft's new in-browser managed platform available on the 3 major desktop contenders.
I remain of the opinion that Silverlight is going to be a major platform for Microsoft, siphoning off a lot of developers who otherwise would be looking at .NET / desktop CLR. And while Mono has not seen the uptake that I think it deserves, the availability of Silverlight on Linux is important for Silverlight's acceptance.