I recently had a problem where I opened the auction house menu and clicked the "Currency" button and got the message saying that the real money AH wasn't available yet. Then afterward the normal gold auction house couldn't be brought up and nothing could be sold because of an error saying "A method of payment couldn't be found on your account". It seems like clicking the currency button switches it to the real world AH, but nothing can be posted and it can't be changed back short of logging out then back in.