http://www.trinityreign.com | Cross-platform, open source 3D IMOW (Immersive Multiplayer Online World) using several open source libraries. IRC: #trinityreign on Freenode.
My inbox is being lit up with updates of code refactoring and enhancements--never been happier to be spammed. Keep up the good work, cigiley!
The project has been worked on steadily for over two years, their are always quite a few members on irc, and it doesn't look like this project will slow down anytime soon.