A research team at Georgia Tech has done something with a smartphone that is both surprising and scary.

You've probably laid your cellphone down by your keyboard countless times.  That's a habit you might want to avoid.

Researchers at Georgia Tech found a way to use a smartphones accelerometer to monitor keystrokes determining what they are simply by the sound they make.

The technique works be detecting pairs of keystrokes and comparing them to determine the key hit.  And it only works reliably with words with three or more letters.  Like most passwords.