Guitar pedal hacking with Arduino/Microcontrollers

[peps1]

Im a big fan of playing bout with Microcontroller and physical computing, and IMHO the Arduino is the pest platform out there for small projects.

I saw this video the other day on makemagazine
http://www.youtube.com/watch?v=_X0bL6WS-VY

And was just wordering if anyone ele has played around with a programmable  Arduino in there stompboxes?