Researchers from Dreamlab published proof that wireless keyboards are very insecure. Engadget writes data logging is fairly easy and requires less than 50 sample strokes for decryption:
According to their whitepaper, "27MHz keyboard insecurities," Max Moser and Philipp Schrödel claim that keystroke signals sent from Microsoft's Wireless Optical Desktop 1000 and 2000 are encrypted with a simple one-byte offset cipher -- meaning that there are only 256 possible keys, with less than 50 sample strokes needed for decryption.
