The Continental application for iOS allows you to just pull up your boarding pass on the screen and have the security screener scan the phone screen.
I would imagine that some of the other airline apps do so as well.
I would imagine that some of the other airline apps do so as well.
(funny thing when I did it was that my screen had a few lines running across the middle of it, so I had to pull down the page and hold so that the QR code fit in the undamaged area)