Elementals are attacking as part of the Cataclysm pre-launch event.
Our friends over at Wowhead just confirmed that the elemental invasion has started as a part of the Cataclysm pre-launch event. There are new quests available in major cities like Stormwind and Orgrimmar, and elementals are spawning in various zones. You can destroy one of each type of elemental rift during the event to earn a feat of strength.
As if that wasn't enough, Twilight Cultists are causing problems in most of the major cities. For more details on the event, check out Wowhead's Cataclysm guide. Let us know how you fare in the elemental invasion in our WoW general forum.