According to IMDB, the Beasties themselves will be played by two different sets of celebrities. In the photo above, we see Seth Rogen as Mike D, Elijah Wood as the King Ad-Rock, and Danny McBride as MCA. There's also another set of Beasties in the film: John C. Reilly as Mike D, Will Ferrell as the King Ad-Rock, and Jack Black as MCA. We also get Susan Sarandon as "mother", Stanley Tucci as "father", David Cross in the role of Yauch's occasional filmmaking alter-ego Nathaniel Hornblower, Orlando Bloom as the Paul's Boutique homeless-dude character Johnny Ryall, and Clint Caluory as "Zach Galifianakis as George Drakoulias," which doesn't make any sense.
Other characters in the film include Jason Schwartzman as Vincent Van Gogh, and Kirsten Dunst, Chlo