I've never really seen what problem passbook is designed to solve. When I get my debit card of of my wallet to pay it's hardly any effort to get my loyalty card out as well, easier, in fact, than getting my phone out. Now, if I've got my phone out to pay then the equation changes. If course, it'd be a bit of a pain having to switch apps from the passbook to the payment app. I wonder if what we'll actually see will be an integration of the two - an API so passbook developers can add a pay option, ie there won't be an iPay app by Apple, you'll use the app belonging to the shop you're in.