Just listened to the director's audio track on District 9. If you haven't, it's worthwhile. He goes into why "intelligently" evolved insects whose queen (the intelligence) had died would be in a heap of trouble in space. He discusses the symbolism of a lot of it--particularly post-apartheid Johannesburg. He discusses the post-apartheid collection of "private security forces" in Johannesburg and what happens when those people suddenly become unemployed (a lot of them are in Iraq and Afghanistan.) He discusses the heroic transformation (if you see it that way) of the main character. He talks about how he wanted the science fiction to blend in with the bland landscape in a very realistic way, and how he had to work to make the bugs anthropomorphized, but not Disney characters.
Oh, and he did it before the film was released, so he had no idea how it would be received. He did come across as a bit more leftist than libertarian, having made more than one negative comment about what we'd call commerce, and another about the mythical fixed-size pie that has to be shared by all.
In short, however, it was a good listen, and he explained a lot. I hope he has a good script for a sequel.