Kompost from Azzor.com reports that Eyonix posted this wonderful gem on the main page and under the General Forum:

We wanted to take this time to remind players that the use of power-leveling services, which generally involves a player paying a person or company to level up a character on the player's behalf, is a violation of our account-sharing policy. The common concern with power-leveling services, and with account-sharing in general, is that sharing access to the account involves players providing their login information (login name and password) to another person. From there, the person receiving this private information is able to do anything they wish with the characters on that account, such as transfer all the gold and items to other players, use the characters in conjunction with hack programs for illicit purposes in the game, and/or delete the characters.

In general, we urge players to refrain from sharing their login information with anyone for any reason, as it's the owner of the account who will be held accountable for all login uses, regardless of whether or not the owner granted authorization or approval. In the event that you become aware of or reasonably suspect any breach of security, including without limitation any loss, theft, or unauthorized disclosure of your login information, please immediately notify Blizzard by emailing wowaccountadmin@blizzard.com.