The folks at CMU's Robotics Institute have released schematics and HEX code for the CMUcam Vision Sensor. With a single-chip CMOS image sensor, Scenix/Ubicom SX28AC75 and a few support components it is possible to build a real-time (16.7 frames/sec) color blob tracker for under $100. Source is available for the asking for non-commercial purposes. Previously stand-alone capability like this was only available in more expensive systems like the Newton Labs Cognachrome Color Vision System.