In an interview with The Playlist (while promoting Dead Man Down), Noomi Rapace (known around these parts for her female badassitude) has confirmed that she has met with Ridley Scott and that a script for a Prometheus sequel (is it is own franchise at this point, or is it still tied into Alien? Whatever) is currently being worked on:
They're working on the script. I met Ridley in London a couple of weeks ago. I would love to work with him again and I know that he would like to do another one. It's just like we need to find the right story. I hope we will.