Tetris Hack on MIT's Green Building
hacks.mit.edu
hacks.mit.edu
Esp. watch the videos from the original Blinkenlights installation in Berlin and the Arcade one in Paris.
However, not sure it qualifies as a hack. Installation of colored lights in the rooms, and linking them to a PC/microcontroller sounds more like a lot of electrician grunt work than a hack.
If they tapped into the existing electric infrastructure, on the other hand...