Okay... a few things worth clarifying.
1- Yes. You can upgrade. You might have to pay more if you've not fulfilled enough of your contract, but here in the US on AT&T, you CAN upgrade.
2- Yes. I am fine (and so are many others) with waiting for a couple months or so to upgrade (My upgrade date is August 24th, and yes, it is accurate).
3- Yes. The more money you spend on YOUR line with AT&T, the sooner you can upgrade. Those of you who have to wait for 18 months here in the states OR for the full 2 years, are either customers who spend less than 100 dollars a month on service OR customers who are 9.99 add on lines of service on someone else's account. Here's an interesting idea for some of you. If the person whose account you are on doesn't want to upgrade soon, have them switch your number to the primary number on the account. The upgrade eligibility on your account should bump up. Sooo... if you have to wait out the full 2 years (or else you have to pay full price to upgrade), and your mom/dad/whomever is the primary on your acccount, yet has had their phone for at least a year, isn't ready to upgrade AND the bill for the PRIMARY line is more than 100 dollars a month, have'em switch you to primary. I've done it before, it DOES work. I've been an AT&T customer since they were Cingular, and before that, BellSouth Mobility. I also worked for AT&T for a year or so back in 2003, so I'm not just blowing wind up your skirt. Give it a shot. If it doesn't work, you can just switch the other number back to primary. It won't cost anyone any money.
4- Gloating is unbecoming, so knock it off, 1st gen owners.

You kept your 1st gen iPhone... great. So did my son. He can upgrade now, but since I pay the bills in the house, he won't be. I will probably use the upgrade if I do decide to upgrade early. He's just glad he has AN iPhone. Besides, he likes the retro 1st gen look.

Also, it is true that many people who have 1st gen are getting messages saying they have to pay full price to upgrade. I get that when I check his account for upgrade eligibility. It's a glitch. They cannot prevent you from upgrading a phone for which you had no subsidy. Hell, he's had his 1st gen since launch. So, I know it is a glitch, and if I decide to upgrade under his number, I'll get AT&T to fix that one for me. No problem.
5- The corporate discount thing... if you have one, you cannot upgrade at the Apple Store. You have to do it through AT&T... but... there's a catch. If you really want to do it through Apple, just call up AT&T, have them remove your FAN number (discount eligibility number... do this like, the day before you plan to buy, just to make sure it's off the account), then go forth and shop the Apple store, friends. Just make sure to take the proper steps to add the FAN number back to your account after you upgrade your phone. It's a bit of a hassle, but so is shopping at an AT&T store.
Finally... Verizon will never sell iPhones, because Apple isn't going to make iPhones that aren't GSM.
Quit going on about it. It's embarrassing. Most of the world is GSM. The US has all these other towers hanging around, that's why we are not fully GSM. Apple isn't gonna start taking backward steps technologically... I mean, they just finally slapped a video camera in a phone that should've had one when it launched in June of '07.
Okay... I know some people will not read that, and will ask the same questions over and over again, but if you need info, there it is.
Happy shopping!