Yeah, after all of the leaks and executive people attempting to move the show to next year, a release date has finally been announced...
April 14th! This year! :D
And rather that having the title The Last Airbender: Legend of Korra in the States, the show's going to just be called Legend of Korra, which is good because that's the name of it in the tags here. ^^;
As a side, here are some more pieces of concept art, from the above Korra Nation tumblr account.
First, the former pro-wrestling waterbender that's been helping out Mako and Brolin,