Dark Sector dev among them.

 From Shacknews

 Along with 2K Boston and 2K Australia, which originally produced and released the game on PC and Xbox 360 last August, 2K Marin and external studio Digital Extremes are aiding in the port's development.

Formed late last year, 2K Marin is said to be made up of several ex-BioShock staffers and has been tasked with the next BioShock game. Digital Extremes' past efforts include Dark Sector (PS3, 360) and Unreal Tournament 2004 (PC).

The exact role each studio is playing in the development is unclear, though 2K noted that Digital Extremes is helping "optimize BioShock's performance on the PlayStation 3."

All four are believed to be working on other projects in addition to BioShock PS3, which could explain the need for multiple studios. 2K Marin is known to be working on the BioShock sequel, while 2K Boston and Australia are rumored to be reviving X-COM.

There has been no indication of Digital Extremes' current internal project or projects.

BioShock is expected to hit PS3 in October with as-yet-unspecified new features and content.. An untitled sequel is slated to hit unknown systems by October 2009.