If it were really that much of a problem, they wouldn't allow any phones to be taken aboard planes at all. On any given flight, there have to be at least 4 or 5 people who don't shut them off (either on purpose or are just forgetful), wouldn't you think?. And we don't see planes falling from the sky on a regular basis. Thank goodness.

As comments on previous posts have said, it's an economic thing. The airlines have no financial incentive to test the devices so they take the stand that they aren't allowed. And frankly, I'm in favor of not having cell phone usage on planes, whether personal or the ones you swipe your credit card on in the back of the seats (do they still have those?!). It's really annoying to have to listen to someone yapping away. But I really don't think it's a safety issue or it would have manifested itself long ago.