Bidirectional OLED microdisplay combines a sensor and a display on the same chip by integrating photodiodes between the OLED pixels:
This technology was developed by the the Fraunhofer Institute. For now the demo chip is only monochrome with 320x240 display and 160x120 camera, but there are plans for higher resolution displays (VGA and above). Here is a video (in German) describing this technology:
Few weeks ago the Silicon Valley startup Pelican Imaging came up with a technology to improve image quality by placing 25 micro cameras in an array. A specially designed software that creates the final image by combining the data from all 25 cameras:
Next is the the "Eyeball camera" developed at Northwestern University and University of Illinois:
"The tiny camera combines the best of both the human eye and an expensive single-lens reflex (SLR) camera with a zoom lens. It has the simple lens of the human eye, allowing the device to be small, and the zoom capability of the SLR camera without the bulk and weight of a complex lens. The key is that both the simple lens and photodetectors are on flexible substrates, and a hydraulic system can change the shape of the substrates appropriately, enabling a variable zoom."