I just printed my United boarding pass for tomorrow, and THEN I thought about Passbook. I downloaded the United app. (AA and Virgin are the only other airlines that seem to have apps so far.) Probably, I won't have a printer available at the hotel for my return, I'll have an opportunity to try it on the return. Has anyone used this yet? Will the barcode just appear when I preboard, or will I have to e-mail it to the phone (not my regular e-mail address)? btw, the Passbook folder renamed itself 'Travel'.