According to The Hollywood Reporter, Paul Greengrass has been signed to direct the Watchmen movie.  Darren Aronofsky has pulled out of the project due to scheduling conflicts.  According to the article, the movie is on track for a 2006 release date. 

 

Greengrass, who directed The Bourne Supremacy, will work from a script by David Hayter, who wrote X-Men and X2, and is scheduled to write Iron Man and Black Widow (see 'Watchmen Movie Announced').