Immediate influences are the high-speed flash photography triggered by sound or light project by Glacial Wanderer and the Laser Triggered High-Speed Photography instructable by Saskview. The first uses a laser break-beam and an Arduino to trigger a flash in a dark room and capture action while the second uses two 555 timer ICs to generate a signal to trigger the camera. The second method does not require a dark room.
The approach described here requires a Canon camera modified with CHDK, uses the Arduino to do the electronic heavy lifting, and does not require a dark room. My intention was to keep things relatively easy -- no etching circuit boards, no cramming stuff in to small spaces &c. That said, there is some careful soldering and fabrication required but nothing beyond that.