It’s a ReacTable Bjork
The very futuristic ReacTable, developed by the music technology group in the Univesitat Pompeu Fabra in Barcelona, is to be used by Bjork on her “Volta” tour. In their press release, the group decribe the device as a “tabletop tangible multi-touch interface”. They then go on to describe its use – “several musicians share control of the instrument by moving and caressing objects on a luminous table”. This, I’ll admit, does sound interesting.
The reactable hardware is based on a translucent, round multi-touch surface. A camera situated beneath the table, continuously analyzes the surface, tracking the player’s finger tips and the nature, position and orientation of physical objects that are distributed on its surface. These objects represent the components of a classic modular synthesizer, the players interact by moving these objects, changing their distance, orientation and the relation to each other. These actions directly control the topological structure and parameters of the sound synthesizer. A projector, also from underneath the table, draws dynamic animations on its surface, providing a visual feedback of the state, the activity and the main characteristics of the sounds produced by the audio synthesizer.

The device does a really good job of visually representing synth sounds – you can check it out on YouTube. Similar visual representation technologies are also used in the iBar and the Human Locator.