Yesterday's Diablo 3 patch 1.0.8 contained a bug that enabled a gold duping exploit that some people, who should be ashamed of themselves (read: well done - can I have some please?), took full advantage of.
Blizzard had to take both the gold and real-money Auction Houses offline, and then bring the game into maintenance to deal with it.
Yet despite the patch only launching earlier that day, Blizzard decided not to roll back the servers to the point at which it was deployed. In other words, the gold dupers still have their cash.
Explained Blizzard community manager Lylirra on the game's forum: "At this time (and after careful consideration), we've decided to not move forward with rolling back the servers.
"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 been able to successfully identify players who duplicated gold by using this specific bug, and are focusing on these accounts to make corrections. While this is a time-consuming and very detailed process, we believe it's the most appropriate choice given the circumstances.
"We know that some of you may disagree, but we feel that performing a full rollback would impact the community in an even greater way, as it would require significant downtime as well as revert the progress legitimate players have made since patch 1.0.8 was released this morning."
Those "corrections" Lylirra mentioned may be temporary locks, suspensions and/or bans depending on the severity of the exploits. It's unlikely any illegally obtained money will be kept. You can read the Diablo 3 Exploitation Policy online, if you like, but it's a bit boring - it's no Song of Ice and Fire.