I can confirm this works. I have a friend who just got his confirmation, and his phone is indeed unlocked. I'm going to be waiting a couple days before trying it out myself though.
I think once unlocked, if you make sure to perform future updates using only custom IPSW files, the risk of a re-lock would be minimal no? Please feel free to correct me on this. Also, I'm not sure how Apple can even identify, or whether they would even bother to identify the IMEI's on their database. There are tons of unlocked iPhones sold every day around the world. I'm sure there's a way, but I'm wondering whether they'll actually bother.
Honestly, I hope this works out... If somebody unlocks and still adheres to their 2-year contract, I don't see what the problem is. Surely very few people actually pay AT&T's outrageous roaming fees to use their iPhone overseas. For example, I have an AT&T locked iPhone, and if I travel, I'll just buy a pay-as-you-go sim from my destination and use it with an old phone of mine. I use my i4 as just an iPod during that time.