Obsidian (the developers) have posted this on their forum...
Rumors have circled around a bit regarding the fate of the Aliens role playing game that Obsidian and SEGA had been working on. Unfortunately, it is true that we are no longer working on the game, and we wanted to finally announce that officially to everyone who has been following its development. We’re going to keep this forum up for another week for archival purposes and to allow you guys to finish up any open threads, and then we will shut it down since it is no longer a product that is in development.
Other games go ahead...
Two other Alien games will go ahead say Sega - Alien v Predator 3 and Aliens - Colonial Marines both FPS titles for the PlayStation 3, Xbox 360 and PC.
Alien v Predator 3