The source is now available at github
The svn repository where MonoTorrent used to be hosted has been replaced by github. You can now check the code out from the git repository hosted at http://github.com/mono/monotorrent . There are a number of benefits for both you and me with this move. The biggest one is that it's now trivial for you to supply patches to MonoTorrent itself by forking the project in github (http://help.github.com/forking).
If you're interesting in following the development of MonoTorrent, add the project to your watch list in github. If you're interested in contributing, fork it and just issue pull requests when your patch is ready. It couldn't be simpler! The first three contributed patches from Olivier Dufour were merged earlier today. Lets get the ball rolling!