A lot of people talk of splintering as if it doesn't exist on the iPhone.

1. different devices have different hardware capabilities: my 1G doesn't have bluetooth, early iPods don't have a camera, etc. Apps have to deal with that on every platform and it'll only get worse as Apple ads more hardware features.

2. different screen resolutions: Android is simply ahead of the game on this one, the iPhone isn't going to stay at 480x320 forever (I'm willing to bet a lot of money next year's iteration will not have that resolution)