Has Warner Bros already cast people for their movie Thundercats?
It doesn't look like it See the Related Links for "IMDb Thundercats" to the bottom for the answer.
Unfortunately, since the movie was first reported in 2007 (see http://thundercats-the-movie.net/2007/07/24/thundercats-the-movie-out-2010/#comment-1475), there's been no movement on it. Current rumors suggest WB are no longer developing it (http://screenrant.com/thundercats-movie-warner-bros-not-happening-ross-39456/). What that means for the future of the property is unknown, but whatever happens it seems unlikely that anything would hit theaters in 2010.