One year ago (september -2007) I had a briefly participation on the pre-production of Blindness the new feature film of Fernando Meirelles (City of God).
I did 2 "almost photo-real - matte painting" style concepts on top of provided set location photos to establish the mood of a city abandoned by blind people.
The city (Sao Paulo -Brazil, but it has no name in the film) goes for that kind of look in a short period, so most of the buildings will not be that dirty, nothing like "post-apocalypse zombie movie city" and all rubbish, rats, cars, vultures and some corpses are related to the street level.
As my participation was very short and I haven`t seen the movie so far. I don`t know how much of the ideas will be there, but I believe that will be a very interesting film with or without it, of course. And it was really cool to do the artwork mixing photos, digital paint and some 3D renders to do all the mess.