Cinematical has the info:

According to Production Weekly, [Owen] Wilson confirmed his role as one of three brothers in The Darjeeling Limited. Wes Anderson will direct off a script written by Anderson, Jason Schwartzman and Roman Coppola. Wait, Roman Coppola? What’s he doing in there? Hmm, this has me wondering if Schwartzman and Coppola will play the other two brothers? Now, that would be interesting. As previously reported, pic will follow the three boys as they journey through India. An assortment of Wes Anderson-style hilarity ensues.

UPDATE: MCN has a review of the script and proposes the theory that the three main characters aren’t entirely fictional:

Then, it smacked me in the face was that this trio of characters was oddly familiar. The three brothers…

Francis… Ford Coppola
Peter… Bogdanovich
Jack… Nicholson

The trio all worked for Roger Corman in the early 60s.