Pretty much everyone who was everyone (or no one) in the '60s has a cameo, from Lance Loud (of the proto-reality TV show "American Family") to David Weisman, director of "Ciao Manhattan" (1972), the seamy, quasi-biographical film about Sedgwick's druggy collapse in which she starred.
WSJ: Book Review: Moments of Being | The Woman in the Dunes | The Decoration of Houses | Erasure | Edie