Well, featuring new Beck as Sex Bob-om (a sly Flipper reference?). Beck made all the music for Michael Cera's character's band in the movie. As an actor, you are going to have someone musically play you, Beck is a pretty cool choice. There is a second soundtrack which features the score in addition to the rock jams, which was made almost entirely by Nigel Godrich, Radiohead's longtime producer. Maybe this is his Mark Mothersbaugh/Wes Anderson moment.