We knew wireless keyboards were potentially vulnerable to eavesdropping, after all, that is the way they are designed to work. This is a bit different, as it affects the traditional wired keyboard:

They've found four different ways to listen in, including one previously-published general vulnerability, on eleven keyboard models ranging from 2001 to 2008, with PS/2, USB and laptop keyboards all falling to at least one of the four attacks. The attack works through walls, as far as 65 feet away, and analyzes a wide swath of electromagnetic spectrum to get its results.
/me goes to make tinfoil keyboard cover

Article is here:

http://www.switched.com/2008/10/21/r...ard-emissions/