@ExXB: Thanks for those insights!
and when you turn your phone over to scan the bar code, it decides to rotate the screen, flip the image, go black or do all sorts of other things to confound the system and make you look just ever so slightly stupid.
That used to be the case with the boarding passes sent as a JPEG attachment in an email. Now, with the Passbook feature on the iPhone in any case, it just simply works.