Apple was recently awarded a US patent for a stereoscopic three-dimensional display system that doesn't require glasses, reported Patently Apple. A scan of the convoluted wording of the patent file reveals a few key points:
1) Left and right eye sub-images are modulated to provide three dimensional images without the need for special glasses.
2) Multiple observers can be accommodated independently and simultaneously.
3) The display will use real time tracking of observers' eye positions to enable realistic horizontal and vertical parallax.
4) A system of tiny-pixel sized mirrored domes are used that are able to change angle based on viewing position.
It's easy to imagine applications in personal devices such as iPhone or iPad. 3D FaceTime and augmented reality apps definitely spring to mind. However, with the emphasis on multiple observers, it is definitely plausible Apple is working on 3D desktop displays or something entirely different as well.