To help keep gamers safe from possible account hijackings in World of Warcraft online, Blizzard Entertainment has introduced a small electronic authenticator that will produce a six-digit security code that can be entered before a WoW player logs on.
Users who purchase the authenticator can register it with their WoW account. Each time they try to log into their account, they'll need to provide their user name, password, and randomly generated code from the authenticator. The only way to have it removed from an account is to call Blizzard and have them manually remove the feature. The randomly generated code is good for one login, and will refresh if not used within 60 seconds.
If lost, owners must provide personal information to Blizzard to have a new authenticator activated and mailed out.
The authenticator can be purchased online for $6.50. Blizzard did not say when the new keys will be released, though did say it will initially be available only for US gamers.
More info: Blizzard Authenticator