Scarry. Just found this on Slashdot.

Posted by simoniker on Thursday May 13, @08:38AM
from the tap-tap-oops dept.
Gudlyf writes "First the blinking LED security issue, now this: listening to tell-tale keyboard clicks to decipher from afar what a person is typing. This isn't limited to just computer keyboards -- ATM's, telephone keypads, security doors, etc. Apparently with $200 worth of sound equipment and software, these keyboard clicks can be translated to within 80% accuracy. Of course, a whole lot of this is just theory."