Blizzard banned some accounts recently for using speed hacks. Quoting the relevant text because, Blizzard and permalink difficulties, et al, ad nauseum, op cit:

Those individuals who were caught using the speed hack have been banned from the game and have had their accounts closed. We must stress once again that we are opposed to hacking and cheating of any kind and are dedicated to maintaining a fair environment in our games. This will serve as a final warning to others who are considering using the speed hack. If you are caught using it, you will be banned without question from World of Warcraft and your account will be revoked.

Cmon man, if you’re going to hack, make it a good one.