I have not heard the entire album yet, but the one single I've heard from Bon Iver's For Emma, Forever Ago is "Skinny Love" and it's friggin' gorgeous. You can hear it at his MySpace page, and you can hear other tracks here.
There's even a Walden-like story behind the album. Bon Iver is a deliberate misspelling of bon hiver, French for "good winter." Justin Vernon holed up in a cabin in the woods of Wisconsin at the start of winter, and out of that came this album.