Nick poses the age-old question: do cell phones really interfere with airline navigation equipment? I remember asking the same question a few years ago, and being told by a friend that cell phone bans aren’t really issued by the FAA, but rather the FCC. Cell phones moving at 500 mph with line of site to many cells tend to create chaos in a system designed for land travel.
An article in Network Magazine confirms my suspicion, and takes it to the next level.. 3G. Apparently 3G phones will be able to hold simultaneous connections to different cells, circumventing the confusion that older phones would give at high altitudes. But this doesn’t mean that the FAA will be loosening their restrictions any time soon. I don’t mind, I’ll just jam the flight attendants’ radar by putting my phone in airline mode.
Wired Magazine: Is Phone Interference Phony?
Network Magazine: Did Cell Phones Save the White House?
overstated 
The last time I flew, I accidentally left my phone on. The plane did not crash. Also, when they are investigating mysterious plane crashes, you never hear the authorities speculate: “well, maybe someone just forgot to turn off their phone….”