I'm glad to see you guys haven't fallen for this as quickly as some sites out there. I first saw this art in a Latino Review article yesterday and decided to do a bit of digging.
My first step - hardly groundbreaking really! - was to contact the artist directly. He has confirmed that, while he is/was working on Prometheus, the artwork shown is NOT from the film.
He points out that he would never post art from a film that is still in early production. Indeed, it goes without saying that to do so would be pretty dumb from a professional point of view.
Much of the art is from one of his own projects, but whoever first reported this 'news' obviously saw on his site that he was working on Prometheus, saw some sci-fi art, put 2+2 together and got about 26!
Of course now more and more sites are reporting the 'news', and needless to say he is pretty p*ssed off about this - it would be great if you guys could attempt to correct the authors of any articles you spot who have simply copied without doing their own checks.
It's shame that such lazy reporting makes people wary of genuine news. scopps and hard work... there's no excuse - I got a reply from the artist within 30 mins of emailing - perhaps that's too long to wait when you have a hot 'scoop'?
</rant over> :-)