"We’ve encountered some difficulty on set with the smartphones. They’re not really props, they’re real things. For example, it’s hard to hide the date and time, or the carrier on the display. If you have a movie without an AT&T agreement, you can’t show the AT&T logo on the phone. It’s very tough to remove that without VFX during post-production. We have to write proprietary apps most of the time. It’s a real device but it’s been co-opted by us. It still has all the interactive functions the phone has but we can control what is displayed and when. Additionally, we can start making it do things a phone never does. That’s the FUI/FUX part."
Timothy Peel designs fake UIs for your favorite films, and talks about it here.