I have had two experiences where a mobile phone has adversely affected the autopilot so I hope the ban during takeoff and landing stays. The further a mobile phone gets away from a tower, the higher the power level the phone uses to maintain contact so in an aeroplane, phones are generally operating at maximum power level unless there is a system installed in the aeroplane commanding the phones to a lower level (as was trialled in a QF B767 a few years ago).