The script for the film version of Halo has allegedly been leaked and reviewed, all online for your viewing
Fan scripts have been called for what they were before, but this one may have the mark of a professional. (A Cinematical post on the story's here.)
Of course, you may question whether it's even possible to write about a script for the movie without dropping spoilers like there's no tomorrow. In the interests of keeping as free of spoilers as possible, you can check out a few reviews (of the review) over at Ain't It Cool News and 1UP instead. The shorter versions help if you're pressed for time as well.
[Thanks, bandersnatch, game-hawg, Carlos, Phil, and Charles]