Here it is... via TTU... edited for brevity...

Q: What is NW's official policy, in regards to using an Apple iPhone in "airplane mode", to watch movies?

A:
1. The aircraft is above 10,000 feet
2. It is not during take off or landing
3. Other portable devices such as portable dvd players can be used
4. the phone is set to airplane mode, which does not use any radio waves that may interfere with the aircraft system

Q:
Does this apply to Airlink partners also (Pinnacle, Compass, etc)?

A:
Yes, it does apply to all aircraft.

I'll keep a copy of this with me, when flying. I'm sure the FA has every legal right to tell me I have to do what they say, yet this should clarify "official" NW policy.

Steve B.