Just came across a book by Richard Slotkin - Regeneration Through Violence: The Mythology of the American Frontier, 1600-1860 which has been referred as a significant influence on Joss Whedon's philisophy. I've never heard of it before, but after doing some reading it makes perfect sense. The book explores the premise that particular stories of expansion and exploration (like those of the Amerian west and Australia's colonisation) re-interpret the violent and brutal facts of history in herioc fairytales. This has particular resonance to the story of Firefly, but also in Buffy.
I've been watching Joss' increasing political activity over the last few weeks with interest. While it seems that he has always been politically minded, he has finally been pushed into public action by the current Bush government. "When I go to Europe, I just want to wear a T-shirt with a picture of Bush and the words: 'I'm sorry'."
Also worth reading is this brilliant article on Joss's politics, Firefly and how the politics are reflected in this work.