Android and iOS device users have had the luxury of using the Battle.net Mobile Authenticator, a software version of Blizzard's downright necessary keyfob authenticator, on their phones or tablets for a while now. As of today, Windows 7 Phone users can also take advantage of the Mobile Authenticator by downloading it from the Windows Phone Marketplace.
At this point, there's pretty much no reason not to have an authenticator -- they're 6 bucks and free to ship for a physical device and no cost at all for a software version available for every major mobile platform. Just get it!
Battle.net Mobile Authenticator for Windows® Phone 7 Devices
The Battle.net Mobile Authenticator, an application for mobile phones that provides an extra layer of account security, is now available as a free download for Windows® Phone 7 devices on the Windows Phone Marketplace. The Battle.net Mobile Authenticator provides a one-time password that you use in addition to your regular account name and password when you log in to a Battle.net account to play World of Warcraft or StarCraft II.
Versions for other mobile devices are also available for download here, or you can purchase a physical Battle.net Authenticator from the online Blizzard Store. Visit the Battle.net Mobile Authenticator FAQ for more information, or head to the setup page to get started after you've downloaded the application.
For additional account security advice, check out our Account Security page.