Mobiles phones expose human habits

The title comes straight from BBC. Its not about good or bad habits but about human movements. Nothing to do with GPS but they've used data from the mobile base station whenever a SMS or a call is recorded.

Conclusion : "humans are creatures of habit, mostly visiting the same few spots time and time again"

More sensors :
"There are so many sensors that you could conceivably attach to a phone that you could do all kinds of monitoring activities with,...
For example, Nokia have put forward an idea to attach sensors to phones that could report back on air quality. The project would allow a large location-specific database to be built very quickly."

Read more about it here.