Here's some good news, for me anyway. I just checked my account and it looks like I'm eligible for an upgrade in 5/2008, meaning my "upgrade" date was not affected by the required 2 year iPhone contract...SWEET.
I agree with all the explanations here. I just thought that an existing customer was getting screwed by jeopardizing their time into an original contract by extending it just for buying the iPhone at full price. Just confirmed that this is not the case...kudos to AT&T for that.
As for my monthly cost, mine was actually reduced by $20/month from my Blackberry plan which is one of the reasons that I got the phone.