These little Arduino boards are a real boon to amateur electronics tinkerers: cheap, versatile, and very small. This guy had the idea to make a high-speed photography setup using one, instead of the more direct circuits usually involved. His reasoning was that the Arduino allows for a lot of easy customization, like for instance hooking up a sound sensor as well as a laser sensor. It allows for failsafes, better timing, and involvement of mixed hardware and software which may in turn control the object drop, speed of projectile, and so on.
I’d definitely be rocking one of these if I had the time to throw down on some sweet high-speed shooting. His gallery is here, but there are more photos over at Hack n Mod.