Can You Use iPhone on Airplanes?

Will you be allowed to use the iPod portion of your iPhone while on an airplane? Most airlines require that you turn off your cell phone throughout the duration of a flight, but how will the iPhone change this?

Will airlines change the rules when the number of iPhone users starts to climb? Or will there be a way to temporarily disable the iPhone’s cell phone aspect, kind of like turning off the wireless card on your laptop? Anyone know?