From recent issue of Wizard...
First of all, Frank Miller and Robert Rodriguez WILL be back. (Of course, I think its pretty much a given that Miller would be back......)
The main storyline is going to be adapted from the 1993 mini-series Sin City: A Dame To Kill For, which takes place before the stories in the first movie, so Sin City 2 will actually be a prequel.....sort of; the main story will take place before the first movie, but the others likely will take place after it. Miller is writing a new story for Nancy that follows her story from the first movie for the film. A Dame To Kill For focuses on Dwight and his former fiance Ava, who wasn't in the first movie. Apparently Clive Owen will be back as Dwight, but Dwight had reconstructive surgery during Dame, so someone else will probably be playing the character for much of the story.
Other tales may be pulled from the 1996 collection of short stories called Sin City: Lost, Lonely & Lethal, which introduced the hitwoman Delia, who is in some of the latter stories.
Dwight, Nancy, Marv, Wendy and Goldie, Shellie, Gail and Miho will be back. So will Bob (Hartigan's crooked partner) in a bigger role. Manute (Michael Clarke Duncan) will be back as well, and we'll find out how he lost his eye. Hartigan *may or may not* be back; if he does appear, it will be a flashback story. Josh Harnett's unnamed hitman character may or may not be back as well, but probably will. (He's called `The Colonel' in the comics, apparently)
Unlike the first movie, which was separated into stories and moved on from one story to the next, the sequel may have all the stories going on at once, switching back and forth between them.
Jackie Boy, The Yellow Bastard, Cardinal Rourke, Kevin (the cannibal), Becky, and Lucille (Marv's parole officer whose hand was eaten by Kevin) won't be back unless they appear in flashbacks.
Danny Trejo will be joining the cast, but it isn't known what role he will play. The actresses rumored to be up for the role of Ava are Salma Hayek, Angellina Jolie, and Rose McGowan.
The movie was supposed to start filiming last month for a late 2006 release, but got delayed until late summer and won't be out until sometime in the first quarter of 2007. (The delay was due to filming of the horror movie Grind House, taking longer than expected.
Interesting fact: Johnny Depp was originally supposed to play Jackie Boy, but had to drop out due to scheduling conflicts. Depp may play Wallace, the former war hero lead character in Sin City 3, which will be based on Sin City: Hell and Back and is tenatively set for a 2008 release.