According to an article from Deadline.com, the Alien Prequel has now become an entirely new film called Prometheus that has resulted from Ridley and co’s work on the prequel:
“First, it started out as an Alien Prequel. But then it morphed into something “more original”, an insider tells us — even though Hollywood kept referring to the project as “The Alien Prequel” right up until today when Twentieth Century Fox officially announced the new Ridley Scott production as Prometheus is now bound for worldwide release on March 9th, 2012.”
The article also confirms Scott cast Noomi Rapace. So it sounds like we won’t be getting a new Alien film. Thanks to Brother and Mikey for the news.