patch 1.08 to Diablo 3's American servers yesterday and, along with it, a very substantial bug. The patch increased the stack size for in-game gold in the auction house from 1 million to 10 million, effectively making gold ten times cheaper. Players then discovered a serious bug: Canceling a gold auction refunded them double the amount listed. Streams of the bug in action soon spread the word quickly. Thanks to the higher stack size, players were reportedly duplicating trillions in gold. Some were buying up high-value items in the auction house, thus driving up prices and massively inflating the in-game economy.
Blizzard became aware of the issue last night and shut down the auction house. As of midnight Pacific, the company had created a fix for the problem, but it still hasn't been implemented. The studio has decided not to rollback the update, and will instead "make corrections" to individual accounts. Writing on the Diablo 3 forums, community manager Lylirra stated, "We feel that this is the best course of action given the nature of the dupe, how relatively few players used it, and the fact that its effects were fairly limited within the region."
We've contacted Blizzard regarding the current status of the problem.
[Thanks, Pablo and Erik!]