Ikiwiki is a wiki engine, and makes it easier for others to deal with it, since they can just use a web browser. Since I don't really use any metadata for bugs, apart from open/closed, Ikiwiki is a simple solution that suits my needs. It's probably not suitable for a large project with lots of open bugs.
I've only just switched, we'll see how this goes. I really hope distributed bug tracking takes off in a big way, however, since it's oh so nice to be able to take full advantage of one's bug tracker even when offline.