just spoke with an American Airlines engineer

[Chyeahhh!!!]

and he confirmed what a lot of you don't know which is that all planes have bells and whistles that never stop communicating with receivers on the ground from the manufacturer of the actual frame and body , any Boeing rep can tell you that. Another thing is that Rolls Royce has the same thing for there engines. All these are built into unaccessible areas that can only be physically accessed when it's on the ground and not in motion other wise the data flow is continious (meaning no on off switches to be tampered with like the transponder) . Rememeber the plane flew for a few hours after that last voice transmission so all this data would have still been collected. FYI