Apple is introducing auto-layout in iOS 6, which will make it relatively easy to design apps which scale to different resolutions. There were at least 3 talks on auto-layout at WWDC 2012.
Only new apps will be able to use auto-layout. I was talking about the backwards compatibility, that is whether existing apps will work well.
From the couple of talks I heard, I think Apple said something about auto-converting 'at runtime' in iOS 6 existing guide-based layouts into the new auto-layout thing based on constraints.
I keep forgetting that I am bound by an NDA. Can't say nothing more.
If your app was well-designed, you have to handle the double status bar on iPhone anyway. This change is pretty much the same as the double status bar.
So: well-designed app might not need to do anything at all.