How is this supposed to be enforced?
1) As Ivor Toolbox mentioned, by security personnel confiscating suspicious equipment?
2) By FAA inspectors searching flightbags for IPods during ramp checks?
3) BY NTSB triumphantly announcing that among the charred remains of the aeroplane, captain's IPod was found ergo he didn't follow the rules so crash is plainly pilot's error?
Person who proposed this reminds me of a certain Spanish AFB. It's not Torrejon.