Here's a long, relaxed Q&A with Charlie at the recent Karlovy Vary Film Festival. It's essentially a film-by-film overview of Charlie's career--no big news or revelations, but still fun viewing, and a few little tidbits I didn't know. He does mention future and abandoned projects like Frank or Francis and Chaos Walking.
One thing worth mentioning: when the interviewer Scott Feinberg gets to Synecdoche, New York, Charlie at first thinks he's asking about Eternal Sunshine, so things get a little confusing for a bit. Other thing worth mentioning: Charlie says Rosie O'Donnell was in Human Nature. But he means Rosie Perez.
Also fun: if a person could only see one Kaufman movie, which one would Charlie pick for them? "Human Nature, simply because no one ever mentions it. Like, you didn't even mention it and no one ever mentions it." That made me laugh.
One final thing: for business reasons, Charlie has a corporation that he's named Projective Testing. The origin of that name is pretty cool--you can Wiki it yerself or watch the video below--and it implies a bit about how he approaches his work.