(HALO TV SHOW 2020 UPDATE - This was posted way back in 2009. It seems the news back then was the same as it is now. No news!)
Responding to questions we had over the Spielberg rumor (and indeed the future of the movie itself), a Microsoft spokesperson told Kotaku:
"We're glad there's still a lot of enthusiasm in the entertainment industry surrounding the idea of a Halo movie. That said, the Halo feature film remains on hold as we focus on projects like Halo 3: ODST and Halo: Reach.
Upon further questioning, Microsoft added that they had "nothing further to share with respect to plans regarding a Halo movie".