Oooh! I'm so excited!
UPDATE: Video and description below!
With the release of new iPhones, and thus new screen sizes, the questions have cropped up again about what is the best way to design universal build apps. The answer for most is starting with an iPad build and then using either stretch (which fudges up your graphics), or overscan (which means you will permanently lose access to parts of the scene due to crop, depending on the secondary aspect ratio). Also, the slight problem is design. If you are using pixel-perfect graphics, both of these will mess you up, since they will down-scale the assets and there is absolutely no guarantee they will stay nice and crisp.
Well, turns out there is a solution. It isn't suitable for all games, but will work for a big majority. Pretty much, if your scene is bigger than your camera, it will work, if they are the same size, it won't (for such games you need to figure out the whole effect on gameplay with changing aspect ratio).
Using this method, you will have no distortion of graphics, and will not be limited by crop factor.
