According to Warner Brothers Animation, we'll be getting a new Thundercats cartoon in 2011. Animation to be done by Japan's Studio 4°C (Animatrix, Gotham Knight, Halo Legends).
http://www.mania.com/first-look-thundercats-return-2011_article_122951.html
http://www.mania.com/first-look-thundercats-return-2011_article_122951.html