World of Warcraft will soon introduce a whole new economy, allowing players both to spend in-game gold on real-life game time and to exchange real-life money for tokens that can be sold for in-game gold.
The system is simple, and best summed up in this graphic (via battle.net):
The new system will launch "in an upcoming patch," Blizzard says, and though they haven't announced specific pricing details yet, they do have a big Q&A (that you can read here) addressing many potential questions. Each token can only be sold once; gold values will fluctuate based on supply and demand; and they're hoping this system will "lead to fewer account compromises and a better game experience overall."
This isn't a particularly unusual move for World of Warcraft, as other MMORPGS (like EVE Online) have already taken steps like this to regulate their gold economies and help crack down on grey-market gold sellers. And although this new system will inevitably lead to speculation about the future of Blizzard's big cash cow, it's worth keeping in mind that WoW still dwarfs every other subscription-based multiplayer game on the market.