To my knowledge, no consumer electronic device has ever proven to interfere with any communications or navigation system (actual transmitters excepted). However, the FAA in their infinite wisdom, says no (non-TSO) electronic device may be used on board any aircraft unless the pilot-in-command has personally determined that such operation is "safe". For part 121 and 135 operators, they do allow the company's ops manual to take the place of or supplement the PIC's personal determination.