The lead developer of Pentabarf is Sven Klemm.
Pentabarf was originally developed for the content planning of the 21C3. The first prototype has been written in PHP. You can find it under tags/0.1.1 in the repository but keep in mind that it's no longer maintained / supported.
The 0.2 version of Pentabarf is a complete rewrite of the 0.1 branch in Ruby using the Rails framework.
Pentabarf 0.3 is a major code cleanup/rewrite of the 0.2 branch.
Pentabarf 0.4 is a major code cleanup of the 0.3 branch. The most important new feature in 0.4 is per conference permissions.