So with the iPad Air, will the T Mobile version be usable on all carriers? If I recall, the T-Mobile version of the iPhone 5s works on all carriers. If that is the case with this new iPad Air, then why is it in Apple's best interest to market four different versions? I just don't get the concept for that. Sure, Apple can have four carriers each selling "their" versions, but from a marketing perspective, I would think that Apple would get a lot more play out of the idea of "one iPad, choose from four carriers". And it'd be great for us...look at the competition it'd create. Heck, T-Mobile's throwing down the gauntlet and giving away data even with carrier-specific versions. Thoughts?