Also interesting:  Could you tell if a phone has been stolen by a change in the walking  pattern of the person carrying it?  An Android app developed by Marios  Savvides and colleagues at Carnegie Mellon University in Pittsburgh,  Pennsylvania, uses data from the accelerometer and gyroscope that come  as standard on modern smartphones to record the movements that a phone  makes as its owner walks. In a study   to be presented this week at the BTAS biometrics conference in  Washington DC, Savvides shows the app can identify a particular gait  with over 95 per cent accuracy. The technology could one day be used to  shut a device down if it registers a gait that does not match that of  its owner  http://users.ece.cmu.edu/~juefeix/btas_2012_felix.pdf