A few weeks ago AppleInsider spotted an Apple patent entitled "Camera as Input Interface" which was originally filed for on Aug. 21, 2008. The patent involved controlling a phone using its camera and described fast forwarding or rewinding of a voicemail by swiping a finger across the camera, or pausing and resuming playback by tapping the back of the phone. It's a simple but very nifty idea.

Apple used simple diagrams to show off the concept but a clever German student has brought the concept of controlling an app using the iPhone's camera to life in the above video. Daniel Bierwirth's "Mobile Off-Screen Pinching Interaction" project isn't exactly the same as Apple's patent but it does involve using an iPhone's camera to interact with an app, or in this case an app running on another device.

There's more information about Bierwirth's "Mobile Off-Screen Pinching Interaction" project on his site.