This is the code from the 2009 Mario AI competition: http://julian.togelius.com/mariocompetition2009/gettingstarted.php
The original code, taken directly from the competition page is in the 'original' branch. I'll keep that up to date as they post updates to it.
The 'master' branch should contain fixes, improvements, examples, and library classes that may be useful to others.
So what're you waiting for? Fork this project and start hacking!
Join us on IRC at irc://chat.freenode.net/#marioai