This week Sega decided to announce a new game in the Aliens franchise, in fact, it was a new game in the Aliens vs. Predator franchise. There was a bit of turmoil when the game was announced, because it appeared as though Aliens: Colonial Marines got delayed when an official spokesperson stated that "..by adjusting the release of our other Aliens titles to accommodate [Aliens vs. Predator], SEGA will ensure that every title lives up to the high expectations of Aliens and AvP fans."
Shortly after a rumor began that Sega, the publishers of the game, had pulled funding from the Obsidian created RPG Aliens as well as Gearbox's upcoming 4 player co-op shooter. According to a Joystiq source, production has ceased on the game because of this.
Talking to a source who wished to remain off the record, they mentioned that it's entirely possible that Sega did though no real evidence exists other than perhaps Sega's financial situation. Current priorities are on Borderlands which is scheduled to ship first, lends itself to the assertion that Gearbox merely shifted focus to strengthen it's development.
Despite Sega's financial difficulties our source told us Gearbox owners could get Aliens: Colonial Marines done through "force of will alone." For now priorities are on another cooperative shooter in Borderlands; I can't say we aren't disappointed, but all isn't lost.