> iPads have different ratio to iPhones/iPod right ?
Ah yes, 3/2 versus 4/3.
> New iPad 3 is rumoured to have Retina display...
Yes, but it will very likely keep the 4/3 aspect ratio, and like the iPhone will scale "non-retina" images automatically.
Totally agree that iOS did not need complexity of the Android SDK due to consistency in Apple product line up but I think they may have dug a bit of a hole for themselves if they want to shake things up in the future.