There are multiple sex scenes. One shows a close up of Nicole Kidman's naked body, including buttocks and her breasts for an extended period of time and also Clive Owen thrusting on top of her.
In another scene it is implied that they are having sex standing up while mostly clothed behind clothing racks in the performers dressing room of a club. I say "implied" because they are mostly clothed and the the fact they are both standing almost straight up with him behind her would make it a very interesting way to have intercourse. They stop when a number of dancers come running down a flight of stairs into the dressing room. A number of the dancers are shown topless throughout the scene as they change costumes and return to the stage. At one point Hemingway covers her mouth to keep her from moaning (even though they really aren't doing much).
The other scene shows a close up of Ms. Kidman's face and a glimpse of her breasts as she climaxes while lying on the bed, the sheets pretty much covering her. it is implied that Clive Owen is performing oral sex under the sheets.
There is a scene towards the end of the movie where naked bodies are shown in a liberated concentration camp. There is nothing sexual about it and it is quite gruesome - there is full frontal nudity though.