Searching the Forums will bring many results, in PAX & SLF, particularly.
Many new phones have an 'Air Mode' that allows you to continue using the organiser, games or whatever aspects but turns off the transmitter. So far, all airlines are barring this as they have no means of knowing the individual units or that the person has indeed turned it off.
Having a phone on in a plane (for a pax) is not worth it. Once the engines and other systems are shut down, any urgent message or calls can be handled long before you even get to your car. Unless you are at a teeny-tiny regional field
As far as I am aware. TWA800 was confirmed as failure of electrical insulation running through the centre tank, coupled with the 'swiss cheese' combination of an almost empty tank that had been heated above normal temps by a prolonged wait on the ground at JFK with the packs running, prior to departure. Again, a serach will tell you. AirSafe.com is one place to start looking.