Everyone's comment's are really right on mark -- technically, yeah, AT&T is following their general upgrade policies, and technically, yeah, people who upgraded to 3G last summer should have to wait until their anniversary date to get the subsidized pricing. Technically.
HOWEVER, there is more at stake for both companies than keeping in line with dates of contracts, anniversaries, and pricing policies.
Even AT&T has "special" policies regarding the iPhone, and even different special policies for business accounts. As the exclusive carrier (in the U.S.) we're all forced to use AT&T. (Mind you, I had AT&T prior to the iPhone as well) -- But once they are not the exclusive carrier, why should anyone keep them as a provider? With all the glitches and network issues, and now the whole MMS/Tethering issue, they really aren't in such an awfully good place to mess with Apple customers! If, like last year, they waived the premium, I wouldn't even *think* about switching carriers. As it stands now, if there is a premium to be paid, I will move my business accounts from AT&T next Friday and will not purchase the new iPhone until my "anniversary." I asked about early termination -- $125 for me. It's cheaper than paying the premium and the $18 upgrade and I won't have to add another 2 years to my contract! That's just DUMB business, no?? If my loyalty to AT&T is not appreciated, perhaps Verizon would rather have my business accounts?
APPLE customers are intensely loyal, and they are the ones who spend hours in line for the new products. I stood in line twice for the new iPhone! All those sales figures reported after the first month of the iPhone releases were from sales to Apple loyalists who adopted early just because it was from Apple. How many people did I convert to Mac computer and the iPhone? How many Apple products do I personally own? TONS!
SO, whatever they do now has a huge impact on their future sales and loyalty base. It's not money in their pocket today, that's true -- however, in the long run they will lose a lot of customers, including me.