On-topic:
I was thinking about setting up a svn on my own personal server, but I guess it's possible to use 3rd party repos as well. We have already documented much of jj2's internals and there have been a number of prototypes to date. Unfortunately the project got stuck a while ago because there didn't seem to be much interest to keep it going. I've worked on the docs for a while later tho. The project's dev forum is here (not much content on it): http://dev.lordprime.com


Off-topic:
Recently I spoke with Pyromanus and he brought a rather big question to my attention. I would like to share this question with outside world to see the response. There have been discussions about a number of different projects and I am rather curious to see which one of them is most desirable and which is most probable. To list a few:

Dedicated server
A server for the current game (1.23, 1.24) with new features, scripting and plugin support. Should use portable code and run at least on linux and windows. This project is probable because we've already documented all jj2 file formats as well as network protocols. The main challenge here is to create a robust internal structure and recode certain parts of jj2 like the engine itself. For such project, I'd likely require some help from experienced programmers (I dare not say any names) to discuss the blueprints and portability (possibly to work on the code as well).

JCS+
Neobeo has worked on this project since forever and the project is currently dead indefinitely postponed. Basically, it's a rewritten Jazz Creation Station with a number of new features. Unfortunately Neobeo doesn't seem to have much time to work on it any more.

OpenJazz2
Like OpenJazz1. A portable, completely rewritten and reverse-engineered version of jj2. Has to support current jj2 standards (networking protocols, file formats and the like). This is basically the same as the dedicated server, but without scripting support and added multimedia (gfx, sound, ui, etc).

New game (1.25)
This project basically gives us the ability to write our own jazz game from scratch. Since this is a new game, it does not have to stick to current jj2 standards. We can implement a number of features that the current game lacks (see the 1.25 thread). While this project presents the greatest reward, it also requires the most work to pull off.