A couple of weeks ago we started the work on porting Microsoft's Media Codecs to Linux and we got the C version running.
Popfly in Firefox3/Linux/x86
Geoff, Fernando and Rolf have been hard at work on this, and have also added the infrastructure to download and install the codecs on demand.
The next step was getting all the assembly language supported in Linux, and today Geoff got the assembly optimized SSE1 audio decoder running (the first chunk of the decoders).
Of course, the rest of the team has been busy fixing bugs and improving the performance in preparation for the first public beta of Moonlight.