As it has more pixels in height, things like GCRectMake that use coordinates won't work seamlessly between versions, as it happened when we got the Retina.
Well, they do work the same with Retina displays - it's just that 1 unit in the CoreGraphics coordinate system will correspond to 2 physical pixels, but you don't/didn't have to do anything, the logic stayed the same. (Have you actually tried to run one of your non-retina apps on a retina iPhone, ever?)
For the actual question: that's why you shouldn't use explicit CGRectMakes and co... That's why you have stuff like [[UIScreen mainScreen] applicationFrame].
