I have a question for the iPhone 3G S. Do we need to have a credit card to buy the iPhone 3G S at either Apple, AT&T, Wal-Mart, and Bestbuy?
I don't think anyone knows since no one has purchased the iPhone 3GS yet. It'll probably be available to be bought by credit card, there's no reason it shouldn't be. Realistically, people don't carry around $200 and $300 in cash.
No you don't NEED one if going to Apple, but if you do cash they need to turn it into a gift card for their system.