This CHDK thing is very cool. I read that page pretty closely and it does some very cool things, but I don't think it will do everything people here seem to be assuming it will do. First if you have a shutter speed of 1/60,000 you will need external light (ie flash) because daylight will not provide enough light. Second I'm not sure they can instantly trigger a shutter actuation. By this I mean that while the shutter speed is 1/60,000 of a second, it might take a few milli-seconds from when you send the 5 volt signal over usb until when the shutter actually triggers. The reason I think this is because they never claim the usb 5 volt trigger causes an instant shutter actuation, and if I had managed to get this to happen I'd be sure to point it out since it's a huge selling point. If anyone knows this usb trigger does cause an instant shutter actuation please let me know.
Oracle, I know that my Canon 580ex flash lets you do the multiflash effect that you were talking about. It is a very cool toy to play with.