Even though Apple Pay --
launched yesterday with iOS 8.1 -- is nominally supposed to be US-only at the moment, it's already working overseas, anecdotes indicate. In particular, the service is functional in Australia, as long as a person is using both US credit cards and region settings on their iPhone. The region toggle is needed to make Apple Pay show as an option.
Beyond that, though, the service
appears to be supported at Australian terminals using MasterCard's PayPass, Visa's payWave, or American Express' ExpressPay. That suggests that Apple's regional boundaries aren't very strict, and that the needed terminal technology is relatively generic, even if
many American merchants haven't upgraded to it yet.
It could also hint that Apple Pay will be able to expand quickly in the next few years, the only real obstacles being partnerships with banks and vendors. Apple has yet to announce any further plans in that regard.