hoax... you can see letterman get to him a couple of time and he cracks a smile. http://www.youtube.com/watch?v=HXpYk7WGN5Y letterman >>> leno
Reading a lot of the stuff on the internet about this whole thing, it's amazing how gullible some people are. If the guy was really so sick of the acting thing, would he be doing so much press for this movie? If he was losing his mind, would his brother in law be filming it? The Letterman interview is hilarious, if only because he seems to know what's up, but still get pissed at how in character Phoenix is and take it up a notch. The "I'll come to your house and chew gum" line had me dying.
He has to do the movie promotion since its likely in his contract. Its probably a hoax but there's no reason for this. He is (was) a big time movie star this isn't helpful to his career. Getting completion insurance for his next movie will be expensive plus marketing gets difficult. The guy looks like Jim Morrison right before Paris. Here's a recent coherent interview: http://www.cinemablend.com/new.php?id=11992 Maybe the hoax is to help his brother in law's career or he might've just lost it. Here's a wierd clip: http://www.youtube.com/watch?v=7F_Ikksg40U This stuff is not good press for a Hollywood movie star.