I can say for sure that iTunes username is not exposed. In fact, they won't even provide an opaque user ID, which makes correlating purchases through in-app pur

I can say for sure that iTunes username is not exposed. In fact, they won't even provide an opaque user ID, which makes correlating purchases through in-app purchase with server-side user accounts very frustrating. You can sort of fake it by correlating with a device UDID, but that is leaky and has a lot of edge cases.