It's not just the home screen/keyboard UIs, though, it's the UI of the apps themselves. Many iPhone apps written for a 4" screen don't feel at all right on a 10

It's not just the home screen/keyboard UIs, though, it's the UI of the apps themselves. Many iPhone apps written for a 4" screen don't feel at all right on a 10" iPad screen (though admittedly some do without much tweaking, like the home screen), so lots of apps would need to come in iPhone/Big iPad/Little iPad versions. Of course, at some point, developers don't care enough to tune for each and every size, so you might end up with a decrease in general app quality. On that note, it'll be interesting to see how Android deals with this. There's certainly a place for 7" tablets... and for 15" tablets, too.