Apple designs great products, and actually includes good access technology on them *for free.* Because the iPhone includes VoiceOver it's quickly becoming the most sought-after phone for blind people. OS X includes a version of VoiceOver that's a fully-functioning screen reader, as opposed to Window's Narrator which true to its name kind of just tells you the high-level of what's going on without letting you actually get much of anything done.
Wisconsin already dropped the Kindle due to its inaccessibility, and despite some rather vague claims of how they're going to hack in some basic accessibility features, Amazon has already shown that accessibility will take a back seat. Schools (secondary and post-secondary) don't want to deal with inaccessible products unless there's a clear advantage - I think this is one case where if you can read books on Apple's tablet they win. Granted there are cost considerations - but the Kindle's already pretty darn expensive for something that pretty much only reads books (most of which you have to buy for $10-20 a pop!).
We in the accessibility field often say that accessibility can differentiate products - I'm really interested to see if this will turn out to be a clear example of that!