Humans are a plague, shredding across the galaxy and destroying other peace-loving creatures. At least, that seems to be the theme of a number of movies that are coming out in the next few years. I've been wondering what would replace the post-apocalyptic-Earth as the stock plot for "dark" science fiction movies, and the evil-humans-in-space plot seems increasingly likely to rule. Among others, James Cameron's Avatar and the new animated film Terra seem to be exploring this theme, which is a standard plot in written science fiction, but is fairly new to the movies. Click through for details.
As I said above, the story of evil humans coming and despoiling an alien planet is nothing new in written science fiction. Off the top of my head, there's Ursula LeGuin's The Word For World Is Forest, among others. I'm almost done reading Jeanette Winterson's The Stone Gods (review coming soon) which deals with this theme. But I can't think of too many movies which have handled this type of storyline. (Enemy Mine, I guess.)
We still don't know all of the plot details for James Cameron's Avatar, coming in 2009, but an early "scriptment" that's reputed to be real includes a lot of information. In a nutshell, Earth is ruined due to centuries of exploitation, and we've used up all our resources. So we decide to go and plunder the mineral wealth of the planet Pandora, whose atmosphere is poisonous to us. Humans can only walk around on Pandora by growing special alien bodies, akin to the native Na'vi aliens. The humans can control their own vat-grown Na'vi bodies, which are called avatars. (We don't know how much of this stuff survives in the final script, but Sigourney Weaver's comments about her character having "her own avatar" make it sound as though it's still there in some form.)