Its all rather silly. I could cut chewing gum sized pieces of C4, use my headphone wires and cellular, IPod, or laptop to privide enough charge to trigger a detonator...boom.
I envision a time where you are not allowed to check in luggage, will have to turnover your carry on a day in advance, have to check into a TSA hotel for a minimum of 24 hours prior to flight and be force fed laxatives, you will be allowed no contact with the outside world prior to flight, be issued a paper travel toga at the hotel, done deal. Perfectly safe and secure travel. Oh...and sleeping gas in the main body of the aircraft.
Unless someone shoots a SAM at you on takeoff or landing.