AT&T is letting people upgrade 6 months early. By doing this they are more stoked about it than you, because now you get a much higher early termination fee contract than what you previously had. Also, the new data limits will ultimately put more money in AT&T's pocket, due to over data limit fees thanks to things like Netflix movie streaming on the 3G and possibly 4G network. Remember, faster cell data networking means greater downloads and thus causing you to go well past AT&T's new 2GB contract limit.
I download a lot on the 3G network with my iPhone. But I expect to pay much more than the $30 per month data plan I currently pay. When I upgrade to the iPhone 4 and have to get a the new AT&T $25 data plan, I can expect to pay more than $30 a month due to overlimit fees. Just one more reason to hate AT&T!