With the auction houses merged, we have to wonder what will happen to the neutral auction houses scattered across Azeroth. Will they continue on as an alternate black market or be eliminated entirely? Facilitating trade between the Horde and the Alliance was the entire purpose of the neutral auctioneers -- a purpose rarely utilized by players for anything other than transferring their own items between characters across faction lines.
Update 11:00 a.m. EDT: We now know that neutral auction houses will become integrated into the cross-faction auction houses. In other words, there will no longer be neutral auction houses -- just one massive interconnected auction house system per-server.