The odd thing is that there is no scientific reason why such devices need to be turned off. Airlines have this irrational policy, and it’s their fault.
Actually, Mythbusters did a pretty good episode on this. No, there's no particular evidence that cell phones or other devices will interfere with the flight controls or instruments on airplanes. HOWEVER... Given a.) the litigious nature of the world, and b.) it is virtually impossible to fully test all of the possible combinations of avionics and consumer electronics that are available. Add to that that new devices and new avionics are being added to the roster on an almost weekly basis. SO: there is no practical way that the FAA or the airline industry can positively ~certify~ that x device is safe on all airplanes, even though it probably is perfectly safe, and so they have little choice but to make these rules about using the devices during key periods of the flight like take-off and landing. Makes sense, given the legal climate.
the best reason for the policy is b/c it got Awec Bawdwin booted off the flight.....