I've always been massively skeptical of the claims about interference (and sorry to those that travel on the same flights as me, I always use my MP3 player during takeover/landing).
If airplane instruments are so sensitive that a MP3 player, iPad, etc., can set them off, I'm seriously shocked. How can they possibly be fit-for-purpose?
I remember when a Merkin friend was flying over with some special tech gear; he asked BA if it was alright for him to carry on his expensive, delicate gear (can't remember the details, some kind of wireless equipment that he was going to use to set up a proof-of-concept long-range wireless network with - pre-WiFi days). They replied that it was fine as long.
He pushed it and asked if he could use some of it mid-flight, and gave them specs; they said that it would be no problem. (He did and said that he found no interesting signals up there)
Alas, this was ~15 years ago, and I no longer have the email that he forwarded around. We were all pretty shocked, though.
Final bugbear: Why don't airlines put the interactive entertainment system on straight away? Passengers would be far calmer watching a film during takeoff/landing.
The system's powered up, so that's not the reason; it's normally showing the stupid "flight info" screen to some boring classical music.
/Beer: need one