At the latest presentation of iOS 7, this feature got a lot of applause and excitement. Such Live Wallpapers have been around on Android for quite some time now.
This Live Wallpaper is called 3D Image Live Wallpaper. It doesn't use much CPU or memory and should even run on outdated Android devices. In the video I used a Nexus S which is quite old already.
You can choose your own picture, or some that came with this app or your phone.
The other Wallpaper showed at the end of the video is GyroSpace 3D, with planets and different layers. So it really looks like 3D objects floating around if you move it.