Speaking with New York magazine's Vulture blog, Up director Pete Docter casually mentioned that he is already hard at work directing his next, currently secret, feature at Pixar.
"I’m mostly focused on the next film that I have in development already. ...I just started. We finished Up, I took some time off, spent some time in Europe and Japan doing publicity over there, so I’ve only been on this for like a couple weeks," he says.Asked whether the project is the long-rumoured sequel to Monsters, Inc., Docter replied:
"I'm not working on ... I'm working on something else, but I cannot announce what it is."
In answer to the next question he suggests a 2013/2014 release date, stating that "it generally takes at least four years, if not five" to complete a feature film at Pixar.
It goes without saying that this is really exciting news. I can't wait to find out what this new, previously unheard-of film is going to be about. But also exciting is the fact that Docter began his response by saying, "I'm not working on... [Monsters, Inc. 2]." (Italics mine.) If you ask me, that wording strongly suggests that somebody else at Pixar is working on it, like so much other evidence suggests.
Check out the complete interview here; it's an excellent read. Discussion highlights include the level of detail visible on the Up Blu-ray and the film's chances at the Oscars.