Jesse summarises Prophet and SD well:
Prophet is a lightweight schemaless database designed for peer to peer replication and disconnected operation. Prophet keeps a full copy of your data and (history) on your laptop, desktop or server. Prophet syncs when you want it to, so you can use Prophet-backed applications whether or not you have network.
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.
All the missing core dependencies have been uploaded to Debian and made it through NEW; Prophet and SD packages will come shortly (1-2 days, likely).
Debian folks may also be wondering when SD will support syncing with debbugs (at least one of you have asked me already). The answer is "eventually, but maybe sooner if you want to help". I started sketching out a debbugs foreign replica type last summer, but it's fallen off my radar since. I also spoke with Lars and Don at DebConf9 about their ideas for a Bug exchange format, which might be worth waiting for debbugs to support.
However, this afternoon I felt inspired to poke around at the old skeleton again and started making some changes. I'll hopefully push a debbugs feature branch that is at least closer in the next couple days, depending on how far I get. Talk to me if you're interested in lending a hand.