According to a job advertisement listed at Gameasutra (now taken down), suggest that SEGA and Gearbox Software are outsourcing the level design of Aliens: Colonial Marines to Timesgate Studios. They are known for their work on the Section 8: Prejudiced.
The advertisement that TimeGate put up stated that they are “looking to expand its team of ultimate badasses working on Aliens: Colonial Marines,” specifically wanted people for level design and user interface.
Back in June, Pitchford talked about the studio looking for development partners for the the game. He suggested some of them put some great ideas on the table. Should be interesting to see, Timegate Studios have improved and their game Section 8: Prejudice was recieved rather well by critics. I see this as a positive.