You can create a 3D effect without needing special glasses. All you have to do is track where the user is looking and render the scene accordingly. You can now try it out the technique on an iPhone or iPad.
When you think about ways of creating a 3D display then you can't help but start to invent hardware to do the job - in particular special glasses that send different images to the left and right eye. In fact you can do much of the same job with just some clever software.
The idea is that by working out the users view point the display can be modified to show what they should see from that position. Looking at the screen then becomes more like looking through a window into another world. Objects in the other world seem to be 3D because they move relative to each other as the viewer's position changes.
This gives the illusion of 3D motion parallax which is enough to convince the brain that you are indeed looking at a 3D scene. It isn't 100% convincing because the view doesn't have "two eye" 3D information - that is it lacks focal depth, convergence and stereopsis. It is 3D only while the view point is changing.
The new system works using the front facing camera on the iPhone/iPad to detect the viewers position and so modify the point of view of the graphics. You can now download it as a free app from the App Store. It works best with the iPad simply because the screen is bigger.
Let's hope that the code is open sourced and how about an Android version?
Clearly this sort of POV tracking technology isn't going to replace full "two-eyed" 3D systems but given the ubiquity of forward facing cameras it is a cheap way to create some 3D effects.