You know what would make me get one? Two things...
1) Ability to become a remote control. There's currently an app for this for the iphone/ipod touch, but it requires a $200 wifi->IR adapter. It would also have to be able to handle communication with the PS3 (bluetooth).
2) Ability to become a keyboard/mouse. Now, this sounds a little silly, but essentially, it's just about having an application that translates keyboard button presses (on the touch screen) into bluetooth commands to send to a PC.
The combination of these two would greatly simplify my living room. Not to mention the fact that devices similar to these will cost you a few hundred dollars a well. I have a Logitech diNovo Mini right now (that cost me $130) and a good Logitech Harmony remote (+ PS3 adapter) would run me between $100 and $300 (depending on how fancy I want to get... such as the nice touch screen one).
But the problem is, if the iPad is anything like the iPhone, then the bluetooth is purposefully crippled and there's no IR port anyway.