Let me expand on this a bit.
- In order to support the new resolution, the app must be built against iOS6, which is only in XCode 4.5.
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XCode 4.5 has removed support for armv6, which is required to build against 3G.
- An app which worked on 3G would be at highest, iOS 4.3.2
- A patch for an app cannot "de-support" older versions: if you build an app against iOS3, you can't drop iOS3 support.
A lot of apps will run into this issue, the farther back the app supports, the least likely it will migrate upwards.