I nagged a long time for it at the company where I work (almost 2 years ), but we now have a public SVN server for Achievo and the Achievo modules. So if you want to develop some code, you can now use SVN for updating your achievo to the latest version. I made an SVN page where you can find all details. A web based SVN viewer is also on the planning, but I will report on it later.
Thanks to this SVN repository I also could add the Achievo project to Ohloh. This site analyses applications based on their source code and full svn history and gives some pretty cool statistics.