I also live in Brazil and am looking to buy this phone. Here is what I know.
a) You CAN buy phones with no committment in the Apple Retail Stores - I just called them up to confirm. US$499 (16GB) US$599 (32GB)
b) However, whether you buy the no committment phone OR a phone with an AT&T plan (and later terminate), the phone remains LOCKED for AT&T use only.
c) My limited understanding of unlocking these phones, is that you CAN unlock the phone via JAILBREAK, however, everytime you update the OS in Itunes it will LOCK and you will have to JAILBREAK again... IS THIS WORTH IT?
d) on EBAY it appears people are selling FACTORY UNLOCKED phones (which dont lock up on updates) for roughly US$900-1000 which usually come from Australia (where they sell them this way), but in Brazil with the price around US$1100, its hardly worth the online and customs risk.
If anyone knows if there is easy technology to unlock the phones permanently please post. I understand this is either a)impossible or b) very complicated to do. Sounds like you need someone to enter a particular code from your specific iphone to a list maintained in the apple server that the server thinks your phone is supposed to be unlocked and that does not lock up. And for this, you need some real connections with apple employees.
Thats what i Know.
Boa sorte!!!
Abs