Miguel De Icaza of Mono fame (and more) posts about the progress they’ve made creating a plug-in for Linux that plays Silverlight content: http://tirania.org/blog/archive/2007/Jun-21.html
The past 21 days have been some of the most intense hacking days that I have ever had and the same goes for my team that worked 12 to 16 hours per day every single day --including weekends-- to implement Silverlight for Linux in record time. We call this effort Moonlight.
Needless to say, we believe that Silverlight is a fantastic development platform, and its .NET-based version is incredibly interesting and as Linux/Unix users we wanted to both get access to content produced with it and to use Linux as our developer platform for Silverlight-powered web sites.
Am now on a flight to Paris to show the results of 20 days of intense work that the team has implemented. It is hard to contribute to the effort sitting on a plane when the tree is changing every 10-20 minutes.
There is technically still some time left to improve what we can show.