Been using one on flights with the wireless turned off for years and fly all over the world, a lot. Never been a problem. If the flight attendant ever asks (which happens rarely since so many businesspeople carry BBs) I say "the radio is off" and they go away.
Not that it would work even if you had the wireless on, way above the towers and signals for them to work and would be hopping cell towers too quick.
Seriously if wireless devices left on does cause major issues with planes or equiptment now is the time they should fix it. If that can take down or interfer that much, terrorists would only have to travel in groups with cell phones instead of bombs and stuff.