Tropic Thunder
This could be brilliant!
I have only just heard about this, but Ben Stiller, Jack Black, Nick Nolte and Robert Downey Jr. (as a black guy) are all in it, in a story where the shooting of a 'Nam movie gets a little shaken and the director simply leaves his cast on location, in Vietnam.
Although I still have reservations in Jack Black, the concept is a great one and Downey Jr. playing a black soldier is walking a thin, yet potentially hilarious line. Again, it's a great concept, but even great concepts turn out poor, a la Be Kind Rewind, so I am simply hoping.
EMPIRE: http://www.empireonline.com/news/story.asp?NID=22137
IMDB:http://www.imdb.com/title/tt0942385/