Presenters at CanSecWest security conference show how they can analyze keystroke vibrations using a laser. Researchers from Inverse Path point a laser on the reflective surface of a laptop between 50 feet and 100 feet away and determine what letters were typed. Using a laptop connected to a PS/2 keyboard and plugged into a socket, the researchers were able to find out what keystrokes were typed on the device. The technology was developed in the US and Canada at the start of the year.
Source: https://threatpost.com/hackers-can-sniff-keystrokes-thin-air-031909/72488/