Catrett Locke Casting, an extras casting company in Atlanta that did casting on Catching Fire, has announced casting on a big new project. While they aren't saying Mockingjay specifically, the clues all point to it!
They recently posted THIS to Facebook
And they tweeted this yesterday. We can't confirm yet that this is for Mockingjay, so make sure to follow CL Casting on twitter and like them on facebook to get the latest information. You can sign up for email updates HERE.