there was a mistake with the advertising and a gold selling advert managed to be displayed on the official wow forums. blizzard very quickly removed it and issued a post.
Recently, there was a temporary error with our forum advertisements that caused a gold-selling ad to be displayed. At this time, we have resolved this error. Our stance, which is fully explained in the statement below, remains firmly against the buying or selling of gold, and we may take action against accounts that are involved in these activities.

http://www.worldofwarcraft.com/info/.../antigold.html
pretty minor stuff but quite funny.