One of the first things you'll need to do with your new iPhone is register with the iTunes Store in order to activate the handset.
Apple revealed the requirement in an e-mail sent Tuesday to those who had registered to receive e-mail updates on the TMHGIH (The Most Hyped Gadget In History). Presumably, most of the iPhone early adopters will be Apple devotees with current iTunes Store accounts, but for those who don't have an account already, have your credit card ready during the iPhone setup process.
Why would Apple do this? For one thing, iTunes is the application that will handle e-mail syncing between the iPhone and a Mac or PC, so registering the device with the iTunes Store might make it possible to wirelessly sync e-mail. But it also gives Apple a way to promote iTunes in front of iPhone users who might also sign up for a Media Max account from AT&T, the exclusive carrier of the iPhone. Usually the carrier controls the services available on a phone, but Apple appears to want that software and services relationship all to itself.