Bethesda has announced a new entrant into the Fallout franchise, subtitled New Vegas. Details are slim at the moment as Bethesda is remaining tight-lipped, but a few bits of information were provided. The game is being developed by Obsidian Entertainment and is due out sometime in 2010 for Xbox 360, PlayStation 3 and PC. The game is not a direct sequel to Fallout 3, though it is an RPG and Bethesda has said that you can expect the "same type of game," despite the fact that a different developer is working on it.
Bethesda did not go into specifics on gameplay or what engine would be used, but a spokesperson did mention that you can "make educated guesses" on those matters. While we're in the guessing mood, we're guessing the game will be set in a post-apocalyptic Las Vegas. IGN has been told we can expect a full reveal when Obsidian is ready to show it.
Obsidian Entertainment was founded by members of Interplay's Black Isle Studio -- the group that worked on the original Fallout games -- after it was disbanded. Bethesda has said it approached Obsidian regarding this project and an agreement was quickly reached. http://uk.ps3.ign.com/articles/974/974295p1.html