I ran across a website that discussed some of the problems that would have to be addressed to create a real-time seismometry system that could exploit the accelerometer that is installed in MAC laptops.
Evil Mad Scientist Laboratories - Proposal: Distributed seismometry
Some enterprising firm has already developed the software to extract the MAC accelerometer data and that is the first important step with any "detector", getting it in a form that is useful to a computer.
