I came across a project called DisTract last week. DisTract is basically a distributed bug tracking system. Specifically, its a file based bug tracking system who's directory structure sits inside of a repository managed by a distributed version control system. It uses this distributed version control system to manage distribution. This system was preceded by another, somewhat bit rotted, system called Bugs Everywhere.
I really like the idea of distributed bug tracking. It fits in really well with distributed version control and over all distributed development. Being able to create new branches for your bug system along with it source. Merge those branches back into mainline all the while keeping history etc. Thats a very, very powerful thing. However, this approach has a fundamental, maybe intractable, problem when it comes to merging. In a version control system merging is relatively simple. Files identifiers (basically the path in the workspace) are fixed there is no ambiguity if the same file is changed on two different boxes. Its just a matter of merging the contents of that file. Distributed bug tracking still has the problem of merging changed bugs. However, it has an additional problem. That is the fact that there is now why to relate on bug created by one person to a different bug created by another person. This is a problem that every bug tracking system has to some extent. In a distributed bug tracking system its even worse because the bugs created by another person wont be visible until they get a push or do a pull from that other persons repository. There may be a way to solve the problem using some of the modern document similarity algorithms. However, considering the small amount of text usually supplied with a bug report this is probably unworkable. I don't have a solution to this yet but I may play around with some ideas and use some information form some of the larger public repositories to run some tests.