Graffiti Research Lab brought their portable lab (AKA matte black school bus). They used conductive paint to create traces to power LEDs mounted in strategic locations. Pictured is one of their programmable controllers for cycling the LEDs.

I have known that you could buy conductive paint for a long time, but I think this is the first time I've see it and begun to see some possibilities for it. Perhaps in an interactive installation where the viewers are invited to create their own circuits?

Thanks to: Maker Faire (Part 2) - Engadget