This is a brilliant idea. Instead of a single server hosting a web forum, apply the principles of p2p software to them and have every forum participant host a full copy of the forum database on their local machine. What you get is excellent security, a forum that’s immune to the slashdot effect with better overall performance in general, and (at least in theory) better search. It’s called Keyforum and it’s free and open source.
It’s a little on the clunky side right now and not easy for non-geeks to get up and running unless you’re on windows where they have an .exe installer, but the intent is to get this running on all platforms. I can see immediate potential for this on campuses where the faculty lack access to sufficient IT resources to bring a forum online for them.