I have a dim view of unbridled cell phone use - no matter where it happens. Sometimes I think people sit at home and make lists of who they will call once in their car and heading down the highway or while ambling down the shopping aisles. It is insane.
I'd love it if people got their cell phone bills at the same time they received the onboard charges printout on debarkation morning. The loud screams and shouts of disbelief would provide an amusing respite while waiting to leave the ship.