Source: http://www.cinecon.com/news.php?id=0407237
Apparently Leonardo will play Tony's role while Matt will take on Andy's.
The Hollywood Reporter reports that Matt Damon will join Leonardo DiCaprio in Martin Scorsese's "The Departed," a remake of the Hong Kong action film "Infernal Affairs."
The remake, which is being headed up at Warner Bros., revolves around a gangster who infiltrates the police department and a cop infiltrates the gangs at the same time. The two find out that a mole is in each organization and race to find each other's identity.
The U.S. version will take place in Boston and instead of Hong Kong gangs, the gang in this version will be the Mafia. Damon would portray the mob's mole, while DiCaprio plays the undercover cop.