Essentially, the machine holds both keys in a straight line. The original key side has a solid, unmovable pin or something, while the new key side has a grinding tool. So when you push both keys inwards, the original key is stopped by the pin, while on the other side, the new key is ground down to match the same point on the original key.
It's hard to explain, you can probably go find a youtube video or something.
But yeah, 21 seconds and $1.99 for a new key. It was quick and awesome.
Also, that Ace Hardware store (@Menlo Park) has so much stuff, despite being so small. And they have bike stuff! And lube that's half as expensive as the local bike store's lube. x.x
Mmm, time to go drink more water. I've got a itchy throat and a cough again. This is very unhappy. :(