Well earlier in the week it was reported that Halo was being shopped around to various outlets after Fox/Universal dropped the project but now it seems the movie is on hold. Likely because nobody wants to pickup the movie for the numbers they are talking budget wise ($200million). Quote from ComingSoon, via FilmStalker
"As was previously confirmed, we deeply regret that both Universal and Fox did not choose to move forward with financing the Halo film under the original terms of the agreement. At this time Peter Jackson and Fran Walsh, along with their partner, Microsoft, have mutually agreed to postpone making a feature film based on the Halo video game universe until we can fulfill the promise we made to millions of Halo fans throughout the world that we would settle for no less than bringing a first class film to the big screen.
We are fully supportive of Director Neill Blomkamp's vision of the film. Neill is a tremendously gifted filmmaker and his preliminary work on Halo is truly awe-inspiring. While it will undoubtedly take a little longer for Halo to reach the big screen, we are confident that the final feature film will be well worth the wait."
So although the HALO movie at this point is not dead, it sure as heck is not moving forward right now. Stay tuned, as we hear more we will let you know.