Following his bizarre appearance on David Letterman's "Late Show" last year, Joaquin Phoenix has been invited on the show again with the release of Casey Affleck's documentary "I'm Still Here".

On Monday the CBS show announced that Phoenix would appear as a guest on September 22.

In February 2009 Phoenix's appearance on the show was uncomfortable to say the least. The awkward silences were filled with quips from Letterman such as "Joaquin, I’m so sorry you couldn’t be here tonight" and "tell us about your days with the Unabomber."

However, the clip had over eight million viewers on YouTube and the CBS site. The clip will also be replayed on Letterman this Thursday.
So far Casey Affleck's movie has been greeted with mixed reviews. Many of its critics are unsure whether the movie is scripted or a documentary and many are billing it as a mockumentary.

The listing of a screenwriter in the credits only further exasperated the critics. Affleck who premiered the movie at the Venice Film Festival insists that the Writer's Guild of American insisted that he include a listing under screenwriter regardless of the type of film.

Affleck insists that the movie is real but added that he had "never seen a movie or read a historical textbook that didn't have subjective treatment of the material."

This weekend the documentary opened to just 20 movie theaters earning $104,500. Much less than expected considering the two year hype leading up to its release.