What is going on with Joaquin?

Joaquin Phoenix looks really bad on Letterman today. The video is everywhere by now, showing a disheveled, spaced out Phoenix mumbling and slurring his way through a truly painful interview. After getting angry at the musician, he sticks his gum under Letterman's desk, and the interview is done. Here is the link, just be warned do not operate heavy machinery after watching this! http://lateshow.cbs.com/latenight/lateshow/video_player/index/php/978097.phtml
There is numerous reports out there about Joaquin's antics, about how he dissed the media here, or bailed on a premiere there, and how he can't remember who Gweneth Paltrow is (who could forget her?) There are also reports of his own people saying this is for a part in a movie about the Hollywood media, and how over the top everyone is; some are saying he's pulling an Andy Kauffman (Ya know, Man in the Moon...no? Ok, see here: http://www.imdb.com/name/nm0001412/)
I would say the role would be more likely than Phoenix trying to be a rapper, I mean, there has never been anything bad to say about him up until now, in fact, quite the opposite, and his film carear speaks for itself. So, it's either he has had a complete nervous breakdown, or it's part of an elaborate hoax. For now, I'm going with the hoax, mainly because I don't like the idea of someone so talented completely losing it. No matter what, the interview was still disrespectful.