A new patent application from Apple details how to implement a 3-dimensional stereoscopic display. While 3d images have been around for years, Apple points out that computational power has advanced to the point where these true 3d images can be rendered and animated in realtime. Apple specifically explores the implementation of "autostereoscopic" systems that don't require the viewer to be wearing special glasses or goggles.
Apple believes its system addresses issues found in previous implementations of 3d and involves tracking the observer to ensure proper rendering of the 3d image regardless of where their exact position. Their system involves real time modulation of left/right sub images to be projected to the observer's left/right eyes individually. Apple also claims it can accommodate multiple observers to provide "a unique and personal 3D visual experience to each individual observer, with each visual experience (i.e., projected image) selectively being similar or different from the others, as desired."
As with all patent applications, we're uncertain when this will make its way out of the labs and into consumers hands, but Apple appears to be continuing to explore alternative interfaces for consumer use. What's interesting is that this is not the first time we've heard of Apple exploring stereoscopic displays. In 2002, Apple was said "to have other flat-panel technologies cooking in the labs, including stereoscopic displays."
http://www.macrumors.com/2008/03/20/apple-researching-3d-stereoscopic-displays/