Ok, the movie was supposed to come out somewhere within the next two years. The Producers are Peter Jackson and his wife. The special effects were going to be made at WETA, the place where they made the Lord of the rings FX. The script was written by the Alex Garland, but then dropped for unknown reasons. The director is Neill Blomkamp. Fox and Universal were supposed to be the companies of this film but backed out because of money. So now the movie is POSTPONED TILL FURTHER NOTICE. If your interested to find out more, check out.
http://halomovie.trivialbeing.net/
http://imdb.com/title/tt0464037/
http://en.wikipedia.org/wiki/Halo_(film)
D.B. Weiss is writing a new script (don't know if it's done) that incorporates some of Alex's stuff.
NO ACTORS whatsoever have been chosen (that anyone knows about), that means no Samuel L Jackson. (for now) ;-)
That should bring you up-2-date