Add Auxo and Zephyr.
Break some more ice between the apps.
Revamp notification center a bit (expandable notifications plus swiping a notification makes it go away instead of that "x" that deletes all in a group.
Tone down the skeuomorphism a bit, the higher the number of pixels, less the need to show gradients and instead go for a flatter design which looks great on "retina". Just look at google apps on iOS.
Allow a plug-in mode where the iOS device can be wired or wirelessly connected to any computer and data transfer is possible like a USB stick. One nice way to do it would be to allow straight transfer to the apps without needing a bloated iTunes program (third party apps already allow wireless, but not wired without iTunes, and stock apps do not allow even wireless, like the ipod app). Make it more streamlined. This is something i think will not happen at least this year though
And, not much else i can think of. The rest is mostly about hardware, so we will leave it to "how would you update/change the iPhone" thread
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