A while back there was a crazy company trying to sell space cameras that could take pictures right onto a CPU that also acted as a display. Those people were insane, but this concept device is far from it. Fraunhofer, creators of MP3 technology, have built an OLED chip with built-in video sensor. That means you can take pictures and show pictures at the same time. It basically overlays two matrices over each other, one for transmitting light and one for sensing light.
The chips contain both an active OLED matrix with a resolution of 320 x 240 pixels and a therein integrated photodetector (160 x 120 pixels). The combination of both matrices in one chip is an essential possibility for system integrators to design smaller devices that make use of both functionalities.
You could feasibly use these in see-through displays or more exotic scanning/display systems. Don’t expect it soon, though. This stuff is still monochrome and it’s not going to get commercialized for a while.