Maybe the mega-grosses of Transformers convinced her, maybe not. Either way, insouciant Sienna Miller has enrolled in the big screen adaptation of G.I. Joe, to be helmed by Stephen Sommers for Paramount, and an August 2009 release date, Variety is reporting. If you read between the lines, she's been cast as Baroness, a raven-haired villain.

In other news, Brad Pitt has up and left Universal's State of Play, a political drama penned by Matthew Michael Carnahan and Tony Gilroy (Michael Clayton), and set to be helmed by The Last King of Scotland director Kevin Macdonald, Variety is also reporting. It's considered an acrimonious split; Pitt left the movie early Wednesday, following two weeks of struggle and meetings with Macdonald that prevented the film from making its original November 15 production start date. The studio considers Pitt to have walked out of a pay-or-play commitment, and is leaving open the option to sue him if the film cannot be recast by next week in time to keep the other actors (a group which includes Edward Norton, Helen Mirren, Rachel McAdams, Jason Bateman and Robin Wright Penn) in place. So... you know, get those head shots in.