My concern is, will people with unofficially activated / unlocked iPhones be able to buy and install the official SDK apps? Because I am sure that there will be many "big" applications which will only be released through iTunes, and for sure iTunes knows whether you have registered an iPhone or not!

I don't want to miss out on all that new software (because I'm sure a lot of it will be compelling and worth the money) but I won't want to be forced into the very expensive airtime contract.