From Rotten Tomatoes:
According to Moviehole, Danny Lerner, executive producer of Rambo IV, has announced that they have inked eight actors for the upcoming film. Similar reports indicate that Lost's Matthew Fox is being wooed for an important role in the semi-anticipated sequel.
Kim Dickens (Deadwood) has been cast as the wife of Rambo, James Brolin (Traffic) has been cast as Colonel Keating, Bruno Campos as an international cult member and terrorist, while Larry Wilcox, Ken Kercheval, Avery Brooks, Randee Heller and Linden Ashby have been signed for small supporting roles in the upcoming film.
Further unsubstantiated (yet juicy) gossip indicates that Walter Hill is also currently in final negotiations to direct the long awaited film."