Josh built this great triple-camera capture unit. With attached intervalometer controller, it captures up to about a frame a second. With 3 Canon T2i cameras, we anticipate getting around 50 megapixels per frame.
3x Canon T2i
3x 128GB SDXC
6x Canon T2i batteries OR 3x Canon ACK-E8 T2i external power adapters
1x Intervalometer (e.g. http://www.amazon.com/NEEWER%C2%AE-Timer-Remote-Control-RS-60E3/dp/B003Q9RERY/ref=sr_1_2?ie=UTF8&qid=1338544370&sr=8-2)
3x 3ft 2.5mm M-M stereo cable (Monoprice 4634)
2x 6in 3.5mm M-F-F Y stereo adapter cable (Monoprice 667)
(OR 2 3.5mm M-F-F Y stereo adapter (Monoprice 7204))
1x 3.5mm F-F stereo adapter (Monoprice 7230)
4x 3.5mm M to 2.5mm F stereo adapter (Monoprice 7126)
1x large external drive
Allen wrenches for adjusting bracket and camera pointing
We're now up to 4 cameras, and are using a custom circuit board with lots of 2.5mm female stereo jacks (lots meaning between 4 and 16, depending on where you trim the board). We found that the 2.5mm-3.5mm adapters from Monoprice were sometimes a bit flakey. And Josh's board allows you to disable the focus signal to the camera, which we believe will be useful when shooting at fast rates. (The intervalometer sends focus early, and for fast shooting rates, basically the camera is monopolized between shooting and having the focus signal triggered, so it's not possible for example to quickly change ISO or other things during the shoot unless you unplug the camera).