When you create a game that lets people trade items and you make some items both very rare and very valuable, you create the demand for a black market. Blizzard has decided to bring cash transactions into Diablo 3; the company has announced the addition of auction houses to the game. You can buy items for gold in one house, and straight-up cash in another. Each region will have a single marketplace, to make sure no currency or exchange issues rear their heads.

"What we've found is that no one's actually done this before," Rob Pardo, Vice President of Game Design, told Joystiq."So it has been a long road to getting to where we are today, where we can actually announce we're doing this."

After you sell an item, you can either remove the money from the game and use it in the real world using an as-yet-unannounced third-party company, or keep it in the game to use on other auctions, Blizzard games, subscription fees, or Blizzard merchandise. While Blizzard won't be selling items directly to increase revenue, Pardo did say that cosmetic items may be sold on the market.

Blizzard is being smart with the revenue coming in from this system: players will be charged a flat fee to list an item, and if it sells there will be another flat fee paid to Blizzard. The company won't make more profit on a more expensive item, and the "nominal" fee will dissuade players from simply dumping everything they find on the auction block. Since drops are random and only players can sell to other players, the economy is still self-contained.

"There are some people out there that don't have the ability to put a time investment into the game, so they do want to use real-world money to kind of advance their character," Pardo told Joystiq. "And the other side of it is that there are people who have a lot of time and don't benefit from it, because they'll be able to generate items, and get better items or cash it out."

Many of the moves here make sense, and Blizzard is creating the market in such a way that it will only minimally impact the game's world. Well, it should only minimally impact the game's world, but we're have to wait until the masses descend upon Diablo 3 to find out how the community will respond.