The high end Chameleon product costs $10,000 and is targeted towards government offices that really need to protect secrets and are willing pay. It works by learning the unique way that a user's eye jumps around while reading, called their "gaze pattern", and calibrates the text on screen to match. To anyone else, the screen sees a constantly changing jumble of text, to the user, he sees a Gizmodo liveblog.
A cheaper, webcam-based version called PrivateEye is just as interesting. It detects your eyes so that if someone comes in the room and you turn away to address them, the screen will automatically blur to obfuscate whatever you were working on. It also displays the face of the person looking over your shoulder in a little video thumbnail so that you can see who's coming in, and that person can see that YOU know he's in the room. PrivateEye is available now on Windows machines for just $20. [Oculis via Baltimore Sun via BalTech]