MichaelMeissner:
While the Hack HD looks like a cool camera, it would be hard to use it with an Arduino for anything other than start/stop sequences, due to the various limits of the Arduino (memory limits, processor speed). And 9MP is kind of wasted on video, since 1080p is only 2.1MP (1920x1080).
Well the arduino can work with a variety of sensors such as motion and light to trigger the record and stop button. Can also help control it wirelessly with an xbee.