Yeah, we still don't know much about District 9, but we do have two trailers and now two posters.
District 9 Poster
To sum up District 9, we have aliens in South Africa. While none of the previews do not show any action as of yet, don't worry, there will be some. If I know Neill Blomkamp like I think I know Neill Blomkamp, some city warfare will take place. An example of this can be seen in the film's first official poster thanks to Yahoo.