According to Sega of America, Aliens: Colonial Marines is a squad-based, first-person shooter that will release in late 2008.  Developed by Gearbox Software, the game will be available on Xbox 360, PlayStation 3, and PC.

Aliens: Colonial Marines will feature a story-driven, single-player mode and an all-new four player co-op mode. In co-op mode, each player will assume the persona of a United States Colonial Marine and have a distinct role to play in the completion of every mission. Additionally, more multiplayer modes will be revealed later in the year that will complete the experience.  Check out the following press release details:

In Aliens: Colonial Marines, players are part of a United States Colonial Marine squad and must prepare to face an Aliens assault more intense and horrific than ever before. Driven by a compelling and original story penned by renowned writers Bradley Thompson and David Weddle, Aliens: Colonial Marines will retain the atmospheric look and feel of the original films while leveraging next-generation technology to create an entirely new interactive Aliens experience.

Packing classic Aliens weaponry ranging from pulse rifles to flamethrowers as well as brand-new equipment and skills all within a squad-based combat system, players will become an elite United States Colonial Marine. Featuring claustrophobic environments, a brooding soundtrack, and a multitude of surprises and shocks, players will battle against menacing alien hordes in strikingly detailed levels that include the stark interiors of the abandoned Sulaco and unique environments created specifically for the game.