I have an Iphone 3G with an AT&T contract. I do a lot of international traveling and I have some news. Sorry if this is not news, but I read the forums and I haven't seen this before. I am in HK now and I have a cheap HK cell phone from Nokia that I have been using for years, very bare bones phone. Anyway, I went to the phone shop to ask if I can use my HK SIM card in my Iphone and he showed me this little thin SIM card thingy. It is really super thin. It fits over my HK SIM card and the two of them go into the Iphone together. Basically it tells my Iphone that the SIM card is OK. Now my Iphone is full function with my HK SIM card. $80 US. It can make your Iphone work with any SIM card, internationally or in the US. Again sorry if this is old news. Oh yeah, and there is no need to jailbreak or unlock. He claims that since you don't have to unlock or jailbreak, there is no chance of a warrantee violation.