To all, I've re-read this entire thread, and A310 has supplied the closest thing to publicly or privately available "facts" for this incident so far. He said:
The Air Transat rudder event occurred when the aircraft was in cruise flight at FL350. There was a strong initial yaw motion. A flight attendant standing in the flight deck was thrown to one side. The event was not precipitated by pilot input and was not reacted to (no counter input). It is possible that the rudder started to delaminate on one side causing the rudder to push over. In this case the rudder subsequently disintegrated due to air loads and drag as is evidenced by the pictures. The vertical stab did not fail because there was no rudder reversal input nor any preexisting weakness in the stab.
Is there any other factual information (related to cause) available at this time?