The pic, which may star Sean Penn and Channing Tatum, is set around the events of the My Lai Massacre. On March 16, 1968, more than 500 Vietnamese (or 367, depending on the source), including unarmed women, children and elderly, were slaughtered by American soldiers who were given a "search and destroy" order. The horrible mission was eventually reported to the American public in November of 1969, and the news led to increased outrage concerning the Vietnam War. Stone already used the massacre as inspiration for a major scene in Platoon, but apparently he feels there's still more to say, and specifically to say, about the events.
Pinkville, if it happens, will mark Stone's fourth film to directly deal with the Vietnam War (if you don't count his student film, Last Year in Viet Nam, or a less-direct film like Nixon), following the "trilogy" of Platoon, Born on the Fourth of July and Heaven & Earth. It should be a welcome return for the filmmaker, as he is, at least to me, associated with Vietnam (and the '60s and conspiracy theories) in the way that Woody Allen and Scorsese are associated with New York. Plus, the subject matter can now be made to have a different relevance -- both Penn, who starred in the Vietnam film Casualties of War, and Stone are probably interested in displaying parallels between that war and the current war in Iraq.