The Legend of Korra trailer was leaked from San Diego Comic Con. It opens with Korra leaving her home in the Southern Water Tribe and making her way to the United Republic. The central premise of Legend of Korra is that it picks up 70 years after the original series and Korra of the Water Tribe is the new Avatar. "The Last Airbender: Legend of Korra" is said to comprise of 26 episodes and premiere sometime in spring or summer 2012.
Of course, as soon as any official trailer or a new trailer is released, you’ll be able to find it here! Enjoy!