Blizzard has banned the first batch of users from the World of Warcraft, as per the article below.
Accounts Banned for Speed Hacking
We wanted to take this time to make an announcement about a serious hacking violation in World of Warcraft, one for which we have zero tolerance. Certain individuals have been identified as using speed hacks to accelerate their characters. This goes against the theme of fair play that we have instituted for the game, and is in clear violation of the World of Warcraft Terms of Use.
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.
Thank you for your understanding and cooperation in this matter. If you suspect someone of using the speed hack, or wish to report other instances of cheating, please email us at hacks@blizzard.com. Thank you again for your continued support.