There is an app for Smartphones that can capture passwords being typed on a keyboard that it is lying next to.

It may seem hard to believe, but by using the accelerometer and orientation sensors built into the phones the app can deduce with a 80% accuracy which keys are being pressed by the vibrations given off and the timing between key strokes.
 
Like hackers that lurk over your shoulder to grap passwords when you are using computer in public places, the Smartphone would have to be placed next to the keyboard that you are using. So it is unlikely that a hacker would have access to your work or home machine.

However, it is just one more way for someone who wants to get at your private information to do so.