Since MonoTorrent is quite features complete. I look for new challenge 
So I have start to work on dirac but I skip it quickly because we have first to work on a more flexible system in for media stream source in moonlight.
I have start to code something where I get out of ogg media stream source the vorbis code and try to make ogg accept other codec as dirac or theora.
I come to conclusion that before done glue I need to have more codec to see all the needs of differents codecs. So I start to code a theora decoder from specification of xiph.
If you want to help, I code on my own branch here:
http://anonsvn.mono-project.com/viewvc/branches/cscodec/
Anyway, it is just a start so do not expect to read a single video, it need a lot of work to achieve it!
What is the progress on this project?
Theora for .NET would be extremely useful, because of Silverlight.
I forgot to mention, we would love to talk to you in #theora on irc.freenode.net, to find out more about your work.
The svn is here:
http://anonsvn.mono-project.com/viewvc/branches/cscodec/Video/?sortby=date
I have currently not enough time to continue but a lot of code have been produce.
I have discover that cortado have a java version of theora it can be migrate to have it quickly….
https://code.fluendo.com/flumotion/trac/browser/cortado/trunk/src/com/fluendo/jheora