Ultima Online producer. OK, maybe the changes at the top aren't that frequent, but it seems like the granddaddy of MMOs has served as something of a training ground for genre producers over the last several years.
The newest commander and chief is Bonnie "Mesanna" Armstrong. The UO website says that her "drive, dedication and knowledge of UO, together with her motivation to kill players (in-game) are well known in the office and among players."
Armstrong hasn't revealed her plans for the game just yet, but the post says to expect news on that front in the near future.