"The reactable is an electro-acoustic music instrument with a tabletop Tangible User Interface that has been developed within the Music Technology Group at the Universitat Pompeu Fabra in Barcelona, Spain by Sergi Jordр, Marcos Alonso, Martin Kaltenbrunner and Gќnter Geiger.[1]"
"The reactable is a round translucent table, used in a darkened room, and appears as a backlit display. By placing blocks called tangibles on the table, and interfacing with the visual display via the tangibles or fingertips, a virtual modular synthesizer is operated, creating music or sound effects."
Stolen from Wikipedia :P

In any case, this is a (bleep)ing awesome instrument thing.

Demo Vid

Improv vid

Dunno, figured it was worth a music chat thread
Think about what this would be like after takin some acid :O

Woah, thats pretty awesome, think about how it would be if you had like 10 guys and one of theses things, .

Are there any bands around that are making songs with this?

That's awesome, you could make some badass Drum and Bass with that thing.