I'll be going to see Penn Jillette and Paul Provenza's The Aristocrats in a couple of hours. The film, which features over 100 comedians and the world's filthiest joke, has a lot of good buzz right now. According to what I've heard and read it tackles taboo subjects and social mores. It's supposed to be absolutely offensive and thought provoking. Censorship and social mores is a theme at Sundance this year. In addition to The Aristocrats, Inside Deep Throat tackles censorship. Inside including one fascinating, if not scary, issue: performers being put in jail for their work! That's some prophetic stuff given the FCC looking to fine folks like Howard Stern and Janet Jackson personally for indecency.
Brandon Griggs reviews the Aristocrat in the Salt Lake Tribune.
The Sundance Channel has interviews with Jillette and Provenza.
The Southpark characters tell "The Aristocrats" joke (spoiler)
Some blog mentions that explain "The Aristocrats" joke (spoiler): here and here.