The work — for those that are interested — is being done in the mathtex branch of the matplotlib subversion repository. This reintegration is especially important as although the success rate for summer of code projects is high (around 80% I believe) a surprising number of the projects never 'go gold' and make it into actual releases. Instead they live their days out in branches and separate repositories.
To ensure that mathtex does not succumb to this fate I have started integrating it back into matplotlib as soon as possible. This has several advantages: firstly it gives the API a good work-out to ensure that there are no glaring issues — reducing the chances that the API will change in the future; secondly it allows for mathtex to have a much wider userbase than it would have otherwise.
While it should not take long to port all of the existing backends over to mathtex the precise manner in which mathtex will be bundled with matplotlib is still up for debate. (But, it is almost certain that it will be bundled, resulting in no extra dependencies for matplotlib.) Once this is done — and tested — mathtex should be on much firmer ground.