Sharp recently made some headlines with the demonstration of a prototype LCD that doubled as a scanner.
The 3.5" LCD screen integrated an optical scanner that could be used to scan business cards, but also be used as a method for multi-touch input.
The screen, on show at the Ceatec exhibition, features an optical scanner for each LCD pixel, and could also be used to recognise fingers or other objects.
The prototype is expected to see commercialization in the first half of 2008.
While not directly linked to Apple, the technology is very similar to an old patent application from Apple which described an "Integrated Sensing Display". Apple's patent described possible uses in video conferencing and photos, but could have also been used for a multi-touch display. Of course, Apple has since come out with the iPhone which offers a multi-touch display. The iPhone, however, uses a capacitance-based touch screen, rather than one based on image capture.
Apple continues to research and develop various touch-based technologies. Their most recent patent applications include pressure sensitive input technology on existing touch screens.