How to get best pricing on your upgrade to the iPhone 3G S

TidBITS has a great article on the eligibility criteria for getting the lowest subsidized price for the new iPhone 3G S. While no one knows all of the criteria, the article explains that it's not simply how long you've had your phone. Another factor, for example, is your account history — and how promptly you pay your bill. Also, the article points out that their system sometimes makes mistakes, and that the only way you can be sure you're getting the lowest possible price is to call AT&T. If you're planning to get the new phone, I would suggest reading this article first.