Blizzard has just revealed that Diablo III will have an integrated auction house that will allow players to trade in-game items for real cash.
While the auction house is to be officially sanctioned, Blizzard won't be selling any items themselves. Instead, it will work much like eBay. You will be able to pay using services such as PayPal.
For those who aren't that invested, a separate auction house will exist which will allow players to exchange items for in-game money, as opposed to their hard-earned cash.