We first heard about the WoW Token awhile back as a potential addition to the game. It was recently confirmed. In summary:The tokens are purchased for actual money (The price isn't set yet, but it won't be less than the regular subscription price.) and are only able to be sold in a dedicated game time token section of the auction house.
They are set to an exact amount, determined by the game rather than the seller, and unable to be bid on, only bought out. Once purchased, the item becomes bound and can only be used to give yourself 30 days of game time. It does not expire nor can it be destroyed.
Basically, it's a way to buy game time with real money and sell it for gold, allowing players to "buy" gold from other players by selling them these tokens - hopefully cutting down on the gold selling problem in WoW.





