I agree with "up2late".
People are just obnoxious and self-centred.
You can give them the information and the resources, and they will still do only as they please. The idea of keeping the batteries (as in the coats) is a really good idea. Maybe a sticker placed on their boarding pass when a mobile phone is detected in their on-board luggage (when going through X-ray/security). This way, when they board, we can see that they have a mobile on them. That will surely screw all those b*****ds that hide their phones for later use!
*feeling more and like a policewoman/babysitter everyday*