FAA Considers allowing Electronic Devices to be used in flight (or takeoff/landing) [DECIDES TO ALLOW IT]

Read the NASA incident reports.

In a few of them, they had to get the flight attendants to really make sure people shut things off, because the compass was being thrown off.

Extremely few and far between. Most planes are using GPS now anyways. If it was a real issue they would have them powered off through the entire flight.

Frankly I never turn them off. I do put my devices in "Airplane mode" but mainly to conserve battery.