it is hard to find a moderately priced digital that can respond fast enough.
Actually, any Canon camera compatible with CHDK (www.chdk.wikia.com) can do 1/60000 shutter speeds (sufficient for high-speed photography) and can be controlled via a quick 5V pulse over usb (which you CAN trigger from an arduino).
interesting... that is fast enough for some of my shots, and it means I can do them in daylight!
but on the page it specifies that is the FLASH speed is 1/60,000, and the shutter is around 1/10,000... than means it is NOT fast enough for some of the ones I plan to attempt... but can that takes sequential shots?