Additional details (from today's Washington Post) which hint at a possible composite failure in the tail section.
"One piece of evidence raises the likelihood that the crew thought the right engine had lost power: The rudder trim setting was found in the crash at a hefty 10 degrees to the left, indicating the crew was using
the long, flat, movable panel at the end of the vertical tail fin to compensate.
"Yet the left engine appears to have torn off first. And some investigators are beginning to suspect that the vertical tail fin and rudder -- found back along the flight path in Jamaica Bay -- actually left the plane before the engines did.
"Investigators found that the fin's attachment points were intact, and that the failure seemed to lie at the base of the fin, which is made up of composite materials. Manufacturers have described the composites as stronger than metal, and the failure raises the possibility that the composites have been overrated."
Jamaica Bay has been searched along the flight path. Visibility in the water is reported as being very good, e.g., tyres can be seen on the bottom, and no other parts of the plane have been spotted there.