See here. Sounds like it’s happening quickly. From the release:
Blizzard Entertainment, Inc. today announced that World of Warcraft®, its award-winning, subscription-based massively multiplayer online role-playing game (MMORPG), is being prepared for release in Latin America. The Latin American localization will be based on the existing European Spanish version but will feature entirely re-recorded in-game speech. This new version of the game will be rolled out in select markets throughout Latin America starting in the first half of 2008 and will also be available to Spanish-speaking players in the US and Canada at that time.
No pricing’s been announced yet. More through the link.