I had heard about this awhile back, but Paul brought it back into my attention and I read more into it:
It's called the Quake Catcher, and its centered out of Stanford and UC Riverside. Basically they use laptops that have accelerometers and if there is an earthquake with a 4.0M or larger, it collects movement data and transfers it to the servers. It sounds like a networked application a la SETI@Home, but way cooler. They are also going to have little USB accelerometers that you can plug into your desktop computer to record motion.
I can't tell you how excited I am for them to get the desktop one out. I can't wait for my Mac to become the official Club Josh Seismometer!