300 became one of the biggest box office hits of 2006 with a worldwide gross of $457 million. Now, director Zack Snyder has confirmed that he is planning on doing a sequel. According to IESB.net, Frank Miller is working on a graphic novel which will then lead to a screenplay for a new film. Snyder recently directed Watchmen, which hits theatres on March 6, 2009. In addition, Miller's The Spirit hits theatres on Christmas Day.