A patent application filed by Apple shows a method for creating three-dimensional depth in a display by using transparent OLED panels in a multilayer construction.
Apple: 3D with transparent OLEDs
Apple’s patent application was filed in January 2010 and describes how three-dimensional depth is created with transparent OLED panels stacked on top of each other.

Apple’s multi-layer 3D OLED display
Because transparent OLED panels require no backlight (traditional OLED panels neither) each panel can show images to the user, creating an illusion of depth. This method does not require 3D glasses but each OLED panel requires a separate graphic driver.

Apple’s patent could allow screens like this one from the Avatar movie
Apple states in the patent application that they believe current stereoscopic displays are not practical for personal use, simply because they require 3D glasses. The patent application is mostly centered on 3D navigation, and not for example 3D movie watching.

Apple’s multi-layer 3D OLED display
The multi-layer display can be used for 3D menus and Apple has showed interest in a 3D user interface for their Mac OS X in the past. Another example is application windows in layers where the active application is lit up and in focus and the inactive ones are displayed on the second or third OLED screen in the multi-layer construction, and therefore perceived as being “further away” from the user.
The patent application is named “Multilayer Display Device”.
- Source: U.S. Patent Office & Appleinsider.com