Absolut Machines
[update] better video of the piece, thanks to Dan for the link.
Absolut Quartet is an “automated multi-instrumental orchestral machine, a large-scale electromechanical sculpture consisting of three instruments and thousands of parts, working together to create one piece of music. The main timbre is a marimba played by balls shot from a robotic cannon. Other components include a series of wineglasses played by little robotic fingers and an array of robotic percussive instruments”
http://blog.makezine.com/archive/2008/02/absolut_machines_amazing_1.html
Absolut Machines at http://absolut.com/absolutmachines with construction videos and web remote control.