I first saw him as a guest on the Daily Show shilling his first book. He struck me as a capable and enjoyable liar. That was pretty much the point of the book, too. When he's on his game he just starts churning out glorious bullshit and you forget to stop believing him.
He is very close friends with Jonathan Coulton. They collaborated on "700 Hobo Names" (http://e-hobo.com)
Hah, in an Onion interview he says a big problem was being mistaken for an genuine paranoid schizophrenic, and The Daily Show enabled his career by assuring people "It's okay, he's not REALLY insane."