This is a difficult year to pick out just five best picture nominees. The Golden Globes put seven in their drama category, but the Producers Guild of America has managed to winnow their single list to five: “The Diving Bell and the Butterfly,” “Juno,” “No Country for Old Men” and “There Will Be Blood.” Over the past 18 years, 68 out of the PGA’s 90 nominees have matched the academy’s, and this seems like a pretty credible list. The most obvious absence is “Atonement,” the former Oscar frontrunner that seemed to get a fresh chance when it won the Golden Globe last night. Less surprising is the snub for “Sweeney Todd,” which seems like an awfully tough sell for the academy. Overall, this remains one hard year to call. For animated picture, the PGA nominated “Bee Movie,” “Ratatouille” and “The Simpsons Movie.”