The Reactable - A collaborative electronic music instrument
The reactable is a collaborative electronic music instrument with a tabletop tangible multi-touch interface. Several simultaneous performers share complete control over the instrument by moving and rotating physical objects on a luminous round table surface. By moving and relating these objects, representing components of a classic modular synthesizer, users can create complex and dynamic sonic topologies, with generators, filters and modulators, in a kind of tangible modular synthesizer or graspable flow-controlled programming language.
The video won't embed, but it's pretty awesome: Current Pod
The project's official website is here.
The software is open source, although I can't see many details of the hardware.