In iOS 4, such APIs do exist. I blogged briefly about it here http://www.bunnyhero.org/2010/08/17/thoughts-on-ios4-camera/ (I used the API for a test app that uses the front camera to detect how much light is shining on the iPhone http://www.bunnyhero.org/2010/08/15/turn-your-iphone-into-a-... )