I remember having spoken about that with Venge, and if i am right, there will be some sort of factions with monsters.
Some will even communicate with each other to \"share\" their \"aggro list\"...
For exemple, is a Guard Lizard (who guards a door) is attacked by a player, and if that player escape him, the Lizard will come back to the door and tell the other Guard Lizards who attacked him, so they will more easily attack the same player, when he comes back. (that s sharing aggro list)