MTV.com spoke with Robert Rodriguez who confirmed that he spoke with both Rosario Dawson and Mickey Rourke and both are pumped to return for the sequel. This is great news because the originals are part of the reason the movie was so great, and an all new cast would worry me. Of course Mickey Rourke's character "Marv" died in the first one, so either this will be some sort of prequel or since it's comic world they'll find a way to bring him back.
Sin City brought us a comic world, gore, and boobs all in one movie....I think a sequel would aim to do the same. I remember reading that Rosario Dawson was supposed to have an outfit that exposed her boobs in the movie, but I guess plans change as she only showed a lot of ass. I'm hoping for the sequel she doesn't mind getting naked like she did in "Alexander."
MTV also brings up a rumor that Angelina Jolie would be cast as the "Dame to Kill For," which would be interesting to say the least although she hasn't been cast yet. Sin City 2 should start filming this summer, so it will be interesting to see who is cast and how many of the original cast end up returning.