We know that old/not updated apps will be letterboxed onto the iphone 5 so there's minimal disruption to the apps people use. But what about apps that are optimized for the longer 5 screen? How will they run on the older 4/4s screen? Seems like a big issue for fragmentation, especially since apple is still actively selling the 4 and 4s. Will the apps be shrunk so the height fits and then letterboxed on the side? Will developers be forced to create both versions of the app? Will apps optimized for the new iphone be ineligible for ones with the older screen ratio, like how the ipad can run iphone apps but not the other way around? I'm not sure how they'll pull this off. I can't see them requiring developers to create 2 slightly different versions of the app, and I think it'll be a mistake to make all updated apps unable to run on the 4/4s. Thoughts?