I am one of the developers at Sparklit, responsible for ActiveBoard.com, a fully hosted forum solution. Activeboard has been providing forums since 2000 (that's right 12 years) using our own custom developed software on a 40 server cluster. We offer free and paid versions and include all the features one would expect.
Yes, this is really great forum. I have used this on some community, great personalization, functionality and more, even if I don't know the technology used
Look here at o0mBBS Revisited