There are three things to look out for in the writing categories: Best Picture nominees (there's always at least one), actors who write (like Matt Damon or Emma Thompson), and the compelling story of a struggling writer who makes a big break (Diablo Cody and Quentin Tarantino come to mind). While there is no shortage of Best Picture nominees in the writing categories and there are compelling stories of struggle, we don't see any actors in the writing categories this year. It's a shame. That always makes things a little more interesting.
the Adapted Screenplay category gives us Best Picture nominees Benjamin Button, Frost/Nixon, The Reader, and Slumdog Millionaire. Filling out the category is Doubt. For this particular award, the adaptation itself must be taken into account. Doubt and Frost/Nixon are based on stage plays and it's often a challenge to move a story from the enclosure of a proscenium into the broad canvas of film. Benjamin Button is a three-plus-hour movie spun from a short story, and the other two are based on novels. I'm going to pick Slumdog Millionaire for the win. More than any other, it uses the source material as a jumping-off point and becomes something purely cinematic. While Doubt and Frost/Nixon retain much of the staginess of their origins, Slumdog Millionaire feels like it was originally intended for the screen.
There's only one Best Picture nominee among the Original Screenplays and I'm picking it to win. Milk comes with a great story: after decades of attempts and false starts, Hollywood wasn't able to make a dramatized bio of the gay-rights activist until a young Mormon came to town and showed them how to do it. It should handily beat Frozen River, In Bruges, and the largely-improvised Happy-Go-Lucky. Its only impediment might be WALL-E, but I'm confident that Milk will prevail.