The fact that AT&T can even offer an unlimited global data plan is evidence that what they pay the other carrier in roaming fees is WAY, WAY below what they charge for data roaming. It's maddening. With voice roaming, I can kind of understand the complexities of call routing through ancient, expensive legacy ATM-based PSTN networks, but data should incur very little to no extra expense--if I'm in Australia and access an Australian website, the data never leaves Australia and is just transmitted to me the same as it would be to my Aussie friend's iPhone right next to me. Optus CERTAINLY doesn't charge AT&T a full cent per KB or even the tenth of a cent per kilobyte that the $200, 200MB package works out to. Hopefully, someday data roaming will be ubiquitously inexpensive (and in line with its true cost). Someday...