A message posted on the studio's website cursorily details the project, only saying, "New team. New console project. Alien IP." Rock, Paper, Shotgun happened to be at The Creative Assembly's offices when the game was announced (how fortuitous!), and learned that the title will be developed by the same crew who worked on Viking: Battle for Asgard.
Additionally, TCA will be growing the team dramatically, opening a "new 10,000 square foot studio" to accommodate as many as 200 workers.
Update: Sega provided Joystiq with this statement regarding the project: "We can confirm work is underway at Creative Assembly on an unannounced title in the Alien(s) universe and the Creative Assembly are looking for highly talented staff worldwide to help in the development process."