"Both developers and files are represented as moving elements. When a developer commits a file, it lights up and flies towards that developer. Files are colored according to their purpose, such as whether they are source code or a document. If files or developers have not been active for a while, they will fade away. A histogram at the bottom keeps a reminder of what has come before."He has visualized well known projects such as Eclipse, Python, PostgreSQL and Apache.
I really liked the Python visualization:
code_swarm - Python from Michael Ogawa on Vimeo.
The rest of the videos can be found at the code_swarm project: http://vis.cs.ucdavis.edu/~ogawa/codeswarm/
It would be nice if the project went open source!