reacTIVision has a midi mode. You will need to start it from the terminal via a special prompt. You can find a lot of info at the reactivision forum hosted
here .
You can also write a patch in PD or Max that will convert the osc-messages into midi.
Tonight I will be presenting some tricks with Ableton Live and reacTIVision here in Barcelona, at the science museum Cosmocaixa. I made some gigantic cardboard-symbols and will give them to the audience, thus converting the audience into an instrument, hehe.
There also will be a presentation of the reactable, with some members of the team that built it.
I hope I get some videos and will post them here.