Blizzard announced recently that they've been wielding the banhammer:

As part of our efforts to eliminate cheating from World of Warcraft, we recently banned approximately 59,000 World of Warcraft accounts in the month of June, and with that removed well over 22 million gold from the total economy across all realms. While we regret having to take such extreme action, these accounts were participating in activities that directly violated World of Warcraft's Terms of Use, including the use of third-party programs to farm gold and items. Such behavior not only negatively impacts the economy of a realm, it diminishes the achievements of those who play legitimately. We will continue to aggressively monitor all World of Warcraft realms in order to protect the service and our players from the harmful effects of cheating.

Blizzard have a solid history of banning cheats, though this post doesn't really indicate exactly what sort of ban was instituted (that is, whether it was temporary or permanent).