Jesse Vincent of RT and Hiveminder fame has just announced that his new system SD is available for public use.
SD (Simple Defects) is a peer-to-peer issue tracking system built on top of Prophet. In addition to being a full-fledged distributed bug tracker, SD can also bidirectionally sync with your RT, Hiveminder, Trac, GitHub or Google Code issue tracker.
You can install SD with the CPAN shell by doing
$ cpan App::SD
For more info, read the release announcement.