Also, see the full frame in the internal camera.app, just double tap the screen and it will zoom out of the cropped mode. (while still only using a middle part of the sensor, though, apparently to allow for the anti-shake to function).
Afaik, all the apps that have a two-spot way of selecting focus and aperture/white balance are faking it somewhat, since there is no official API to control the camera that way. Of course, most of the time the results are quite ok.
The usual method using just the built-in camera.app would be to first lock on to some spot thats both in the right distance and has the right brightness to achieve the correct look, and then just frame the scene by moving the iPhone in the recording position.
But I don't know how often I wished for more flexible ways to setup the camera manually :p