Blizzard has issued a warning to World of Warcraft players stating that they've seen a recent spike in unauthorised log-ins via the their website, and through the mobile armory app.
Those directly impacted by the log-ins have been notified via email, with instructions to reset accounts. As an additional measure, the mobile app in question has been taken off-line temporarily, while Blizzard can get to the bottom of these latest incidents.
Maybe a good time to change that password...