#0 - Oct. 29, 2007, 2:23 p.m.
Blizzard Post
We currently have no announced plans to give players a 3rd profession. Doing so may take away from the community aspect of this multiplayer game and we'd rather just have people choose carefully and talk to others when they need things from other professions.

This information was posted by my good colleague Bornakk on the US forums:
http://forums.worldofwarcraft.com/thread.html?topicId=2517899314&postId=25741581541&sid=1#2