I'm Just Crewman Number Six
I haven't seen everything that Sam Rockwell has ever been in. He's got 66 credits, and many of them run to the incredibly obscure. However, with the exception of Welcome to Collinwood, I've liked every movie of his I've seen, and I even dug Rockwell in Collinwood. He's not an actor that's easy to dislike, even when he plays deplorable bastards (Snow Angels). Moon is the lone exception -- I disliked the movie, and I even felt that Rockwell was far too restrained in it (for my money, I have no desire to see a restrained Rockwell, not when he plays unrestrained so well). Nevertheless, I do respect the hell out of the guy's movie choices -- he doesn't pick easy-money projects, unless they're worthy of his talents (see upcoming Iron Man 2).
I was, however, in the minority of people who didn't like Moon, among the several of us who saw it at SXSW. I'll just chalk it up to the fact that it's an overly cerebral sci-fi flick and not just a slow-moving snoozer that built, interminably, toward an anti-climactic finale (I felt similarly about Steven Soderbergh's Solaris, though I can concede it was a well-made film).
Moon was directed by Duncan Jones and, in addition to Rockwell, included the voice of Kevin Spacey, who did the voice-work for the film's robot. Here's the trailer.