These last days I had fun with Padraic Bradys MutateMe project. It dynamically changes your code (using PECL Runkit extension) and checks weather your test cases fetch the errors occurring from changing the source code. This is a great addition to having a test suite, because it finds all the problematic test cases, that try to do too much and fail to cover the code correctly.
I have also contributed to the MutateMe project already and this was only possible due to Git and GitHub, which makes contributing to any project easy like writing a hello world example in a random programing language. As such I have to agree with Padraic: I love Git, too! He already integrated my and Sebastians changes back into the master and we didn't have to focus on merging, communication and integration a lot.
My PUMA project is also hosted on GitHub (although nobody has looked into that yet), but I am beginning to write a complete Runner now that calls all three components PHPUnit, PDepend and CodeSniffer at once and directly processes the results. When this is done, I will pack it all up as a PEAR package for anyone to test out.