We reported last month that Joshua Zetumer is taking over screenwriting duties on the project. Since the screenplay is still being written, it seems unlikely that any serious offers will go out to cast members until a draft is done.
RoboCop would provide an interesting challenge for A-list actors such as Tom Cruise, Keanu Reeves, and Johnny Depp, since their face would be obscured by that metal mask for a good portion of the movie. However, Robert Downey Jr. pulled it off just fine in Iron Man.
It isn't known when production will start on RoboCop, though a 2013 release date is being considered by MGM. The original 1987 Robocop starred Peter Weller as a Detroit police officer who narrowly escapes death and is revived as a half-man half-robot crime-fighting machine.
RoboCop was released February 12th, 2014 and stars Joel Kinnaman, Gary Oldman, Michael Keaton, Abbie Cornish, Jackie Earle Haley, Michael K. Williams, Jennifer Ehle, Jay Baruchel. The film is directed by José Padilha.