A reader of this blog saw The Messenger yesterday and gave a detailed report of the nudity in the film.

The JM scene is literally two minutes into the film. Jena Malone plays Kelly, Will Montgomery(Ben Foster)'s ex-girlfriend who picks him up when he returns from service. After an awkward greeting, the scene abruptly cuts away to the two having sex at his apartment. The whole scene is about 30 seconds long; the first 10 showing Malone riding Foster (back and ass) then switching to Malone on her back showing mostly her right breast. The second part of the scene is dark, but you can definitely see that it is her and not a double.

About 25 minutes in, Emily (Lisa Joyce) is shown dressing, presumably after having had sex with Woody Harrelson's character. Well-lit scene shows full-frontal and brief ass. About 10 seconds long. (I'm not positive this is Lisa Joyce... just narrowed it down from IMDb credits)