A recent update (1.08) to Diablo III introduced a gold duplication glitch that sent the real money auction house into a cycle of hyper inflation. As of this writing, the auction house remains down as illegitimately gained items continue to expire. The alternative was to rollback the server to a previous version, but as stated by Blizzard, this would also remove any progress from legitimate players:
“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 know that some of you may disagree, but we feel that performing a full roll back 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.”
No solid ETA has been given for the return of the auction house. Gold trades remain disabled for all players until Blizzard is certain they have locked down the issue, and those players who exploited it have been dealt with.