In 30 years I am not become aware of any aircraft accident being caused by a bunch of kids in the cabin using portable game machines; idiots trying to use mobile phones; by the use of laptop; vibrators or allowing passengers with heart pacemakers.
I am aware that pilots have reported erratic cockpit nav and control indications from time to time - and when cabin crew have been asked whether anyone in the cabin is using an electronic device often the answer is yes - of course when you have 250 people behind you some kid will be playing with his gameboy - or nowadays his PSP2 - but what is cause and what is effect.
Maybe there was something in the wiring or in the hold - or the pilots fingers and/or attitude.
I understand (and I am no longer in the field) that no aviation safety authority has been able to duplicate control, nav or instrument deviation with non-transmitting devices being used in the cabin.
Its like saying are there any blondes in the cabin - yes. Then blondes guys cause intrument deviation.
I of course stand to be corrected - but MP3 players will not cause your aircraft to crash
Barkly
I think you fail to understand the basis of airline safety policy. Aircraft safety concepts are built on removing every conceivable factor that
might have an influence, of some type, on the normal operation of a plane. It's probably true that MP3 players don't cause accidents, no-one really knows what effect an MP3 player has on aircraft(s) (remember there are hundreds of different types) on every conceivable landing situation. Furthermore, no-one knows what effect an electrical device being used in row 1a may have on elctrical device in 17b in a particular landing situation, say in an electrical storm, and no-one really knows if said devices would have an effect on instrumentation being used by the crew flying the plane. Remember, most accidents are caused by a chain of events and not one particular and obvious thing.
Your points about an emergency during cruise could be answered by saying that when at 11000m it would be probable that the crew may have more time to identify a problem, if they are 20m from the ground and about to land they may have less than a second to arrive at the correct conclusion and take decisive action.