I really dig the end result of this hack. Using Quartz Composer and TUIO, this project dubbed "Stretchy Lines" has came to life thanks to that handy depth sensing wonder toy Kinect. The setup includes a Kinect perpendicular to the table. The TUIO Server detects objects within a specific range, and then a calibrated projector draws random lines around the objects detected.
TUIO sends objects coords using OSC protocol to Quartz Composer, and then the graphic is rendered using custom Quartz Composer patches.