Blizzard Entertainment today announced that World of Warcraft has sold more than 600,000 units in North America, Australia, and New Zealand, with over 200,000 simultaneous players online during the holiday period.

"The publics response to World Of Warcraft has been simply amazing," said Mike Morhaime, president of Blizzard Entertainment. "We are very proud and excited to see such an overwhelming demand for the game, and we hope that the enthusiasm continues to build as we further enhance our online service."

We reported earlier that demand for World Of Warcraft was so great, retailers sold through most of their supplies first week, and therefor Blizzard was putting a hold on further delivery. After a short and successful testing period to ensure server stability, Blizzard will be bringing additional servers online and plans to release additional units to retail outlets nationwide.

Since the World of Warcraft launch several features have already been introduced, and in the near future, the promised Player-versus-Player (PvP) Battlegrounds, as well as the PvP Reward System, will be revealed.