I was just on a flight from Japan and I can't remember if it was JAL or AA that specifically singled out "wireless ports" by announcing that if we had them on our laptop, we had to ensure they were turned off. Before I shutdown, I ran Stumbler and found two other machines with wireless active so I guess I wasn't the only one.

I think the scientific studies are still all up in the air. I remember once during a one hour layover in LAX, I talked with the pilot about cell phones and he said once on a flight they had a massive burst of interference that coincided with someone (wrongly) using a "palm-like cellphone device" in midflight (I think they forgot to turn it off and got a call). As soon as they hung up and turned off, it was better.

The pilots called ahead to the FAA or the airlines and they worked out a deal with the passenger where they would take his phone/palm (or get it sent later) and replace it with a new one. They then tested the exact same phone and couldn't recreate the situation described.

Anyway, just an anecdote but from what I've read all the problem reports have been anecdotal.