We also wanted to reassure you that the Battle.net Authenticator and Battle.net Mobile Authenticator (a free app for iPhone and Android devices) continue to be some of the most effective measures we offer to help players protect themselves against account compromises, and we encourage everyone to take advantage of them. In addition, we also recently introduced a new service called Battle.net SMS Protect, which allows you to use your text-enabled cell phone to unlock a locked Battle.net account, recover your account name, approve a password reset, or remove a lost Authenticator. Optionally, you can set up the Battle.net SMS Protect system to send you a text message whenever unusual activity is detected on your account, keeping you aware of important (and possibly unwanted) changes.
We also have other measures built into Battle.net to help protect players. Occasionally, when Battle.net detects unusual login activity that differs from your normal behavior -- such as logging in from an unfamiliar location -- we may prompt you for additional information (such as the answer to one of your security questions) and/or require you to perform a password reset through the Battle.net website. World of Warcraft players might be familiar with this security method already, and Diablo III players may begin to encounter it as well.