This is sort of off-topic because it's not using Mathematica, but this[1] is another really neat intruder detection system that I've found that's surprisingly accurate.
It's based on a technology[2] created by the guy who made Palm.
And here's a guy trying to fool it and mostly failing.[3]
[2] http://www.numenta.com/htm-overview/education/HTM_CorticalLe...