Beau Giles figured out a way to use Apple Pay, currently limited to the US, in Australia. Essentially, given the right settings and card, Apple Pay will treat the user as an American tourist in another country, with an obvious consequence:
Unfortunately, as you’re essentially paying with a card from the US, you’ll be paying currency conversion fees for anything you buy in Australia with Apple Pay.
I have tried this myself, and I could show the Apple Pay setup screen in Italy, but I don't have a compatible American credit card. It's too bad, because the MasterCard Nearby app shows plenty of Contactless-enabled stores in my area.