The new version of iOS 7 includes a Parallax feature for the home screen. This gives iOS a 3D effect, but doesn’t require the 3D.
This works because the onscreen graphics are arranged in multiple layers. The icons are on one layer, and the wallpaper is on a second layer. When the iPhone tracks your motion, the objects in the foreground move faster than the object in the background. This creates the illusion that they are closer to you. It’s not like having a 3D screen, it’s more like a simple 3D effect.
This image from Wikipedia gives you a good idea of what parallax looks like (If image doesn’t work, click on it):
iOS 7 does something like this by moving the icons according to how you tilt your iOS device, presumably by using the accelerometers and gyroscope. It sounds a bit awkward, truth be told, but we hope it works well when we get to use it. We’d hate for it to tilt things too askew.
Read more about Parallax here.