I can't prove it, but I am pretty sure that my iPhone causes the Garmin GNS 430's in my plane to have an "INTEG" error. It does not happen if I put the iPhone in airplane mode.Granted, a few cellphones/laptops on an airliner have a very slim chance of causing interference to the electronics, but if you allow everyone to use their electronic gadgets, no one knows what 250-400 cellphones/laptops all operating at the same time can do. The cellphones will probably be operating at max power, albeit several hundred milliwatts,but there are thousands of opportunities for intermod aboard an all-metal aircraft, so who knows what RF products will be polluting the airwaves with that many transmitters in such a small space.I'm for keeping the rules and maintaining some quiet in the cabin. Can you imagine the noise with everyone trying to talk on their cellphones in business class?Also, any ham radio operator can tell you that electronics can and do emit RF interference on the HF bands. Oceanic flights use HF to report positions and receive other pertinent flight information. It would be pretty annoying to the pilots, if not downright unsafe, to have your flight's HF communications blocked or interfered with by someone's cellphone or other piece of electronics. I know, they are all supposed to comply with FCC Part 15 for incidental interference, but that is not always adhered to in the real world, and that only applies to electronics that is in proper working condition.