Wouldn't this require custom APIs? If not it sounds like an awesome idea, but if it has just 1 custom API (as you probabl know) Apple won't accept it.
I thought about this an year ago and researched to find a solution to do it. Actually apple doesn't allow to talk to non apple certified devices as Jermey mentioned earlier. I actually hacked the bluetooth format of ps3 and was able to talk using my macbook pro. It's just a python script I used so doesn't matter that it has to be mac. Jailbroken iPhones for sure is the way to go. But I'm not sure if any one would take the pain.