Preview at WWDC likely in June, followed by September launch.
Apple: Stereoscopic Displays and Wearable Computers?
Stereoscopic Displays and VR Systems III Preface indicates Apple demonstrated the following in 1996:
A prototype wearable computer system from Apple Computer with a Virtual I/O head mounted display
As well, this paper Volumetric Hyper Reality, A Computer Graphics Holy Grail for the 21st Century? (1995) indicates some interesting research in "Hyper-Reality" displays, providing environmental feedback in images (reflections/transparency):
An incremental steps towards a hyper-display is shown in Figure 20. It shows a 2-D display with a micro-camera focused on the user. A second camera points backwards away from the rear of the screen. Using the data from the cameras, and special algorithms, it is possible to apply an approximate transluminance matrix for the specular reflections and refractions in a scene, in near real time. An early prototype of such a system, using a single camera, has already been built in our lab.
Related Article: Apple: Stereoscopic Displays?