I just got off of online chat support from AT&T and this is what they had to say:
You are now chatting with 'Shamere L'
Shamere L: · Welcome to AT&T Premier Support, my name is Shamere. I am reading your question and will be right with you.
Shamere L: Give me a moment to pull up your upgrade status.
Shamere L: Our system states that your last upgrade was 06/29/2007 and your contract will end 06/29/2009.
Shamere L: So you wouldn't be eligible until closer to your end of contract.
Brandon: I purchased an iPhone on 6/29/2007 and I paid full price. It did not remove my upgrade elligibility
Brandon: Yesterday my account said that I am upgrade elligible, and today when I logged in, it says that I am not. I would like this to be fixed please.
Shamere L: Ok, Thank you so much for your patients, you recently did an upgrade online and returned the device correct?
Brandon: That is correct. I returned the device within 30 days and my upgrade status was restored, until today.
Shamere L: Ok, I do apologize for the inconvenience, I see that change, what we can do is if your wanting to purchase a device, we can order the device for you with the online prices, I do apologize about this.
Brandon: I plan to go in to the store tomorrow morning to purchase the new iPhone 3G. I need to be upgrade elligible to get the $199 price. Will I have any problems doing this?
Shamere L: No you won't have any issues, being that this is all in your account notes and I will note your account as well to make sure you have no issues when purchasing the new Iphone 3g.