We saw a project earlier this month that worked like an Ambilight system but this open source Light-Pack USB Ambient Lighting System seems to have much better effects. And since it’s open source you can get all of the info you need to make your own. I can’t wait till there is a system that doesn’t requite a computer to process the image.
“The software analyses the image on your monitor and transfers its data by USB to the Ligthpack board. This board lights the surface behind a monitor, TV or laptop by means of RGB LEDs of the corresponded colors.”