Let me quote from Boing Boing
This paper won the Outstanding Paper Award at AAAI-04 (Amer. Assoc. for AI's National Conf.) in July. In a nutshell, they took the trace from a person carrying a GPS unit around with him for a month. With no hand labelling of the data, they were able to build a model of the person's travel behavior including frequent destinations (work, home, grocery friends homes), and modes of transportation (bus vs. walking). With new data, the model can predict, on-line, the traveler's most likely destination, and detect 'unknown activities' (e.g. strange behavior).
Incredible feat for AI, but pretty chilling development when you think about Big Brother.