Pressure has been mounting of the Federal Aviation Administration to change rules requiring that all electronic devices be turned off during takeoff and landing -- the periods during which even slight anomalies in instrumentation could cause potentially disastrous results. The problem is that the evidence that a cell phone or GameBoy could cause such anomalies has long been questioned. This week, the FAA is expected to finalize its recommendation to heed this fact and relax the restrictions on the use of cell phones at any point in a flight.