According to Kotaku it looks like the Halo movie is "on hold."

Last weekend, it was announced that Steven Spielberg would be producing the project. Now, according to Microsoft, it looks like the film isn't doing much of anything.

Regarding the recent rumor that Spielberg would be working on the project, Microsoft said:

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.