http://us.blizzard.com/en-us/securityupdate.html
Looks like someone got into Blizzard's network and got Battle.net information for non-China accounts. They are recommending that people update their passwords, and they will soon provide a link to update security questions, as well as new versions of the smartphone Mobile Authenticators. The physical authenticators are apparently not affected. There is additionally an FAQ at the link below.
http://us.battle.net/support/en/article ... update-faq