This article caught me by surprise. Or I had forgotten a film version of Big Sur was in the works. It really is an amazing novel, and I'll be interested to see the end result. Here's another link if you're interested.
According to IMDB, Kate Bosworth plays Billie, Josh Lucas plays Neal Cassady, Anthony Edwards plays Lawrence Ferlinghetti, and Jean-Marc Barr plays our hero, Jack. Here's a pick of Jean-Marc. I suspect he wore a wig for the film.
Do not confuse this with One Fast Move Or I'm Gone: Kerouac's Big Sur, an excellent documentary released a couple of years ago.