The cast has been revealed: http://forum.newsarama.com/showthread.php?t=122573

Patrick Wilson as Nite Owl II
Jackie Earle Haley as Rorschach
Billy Crudup as Dr. Manhattan
Malin Akerman as Silk Spectre II
Matthew Goode as Ozymandias
Jeffrey Dean Morgan as The Comedian

I think Crudup, Goode ("Match Point") and Morgan ("Grey's Anatomy") are great choices. I'm not really familiar with the others, but I'm glad they didn't go with a big name for Rorschach.