The original Mass Effect included a New Game+ option, but it was omitted in Mass Effect 2, with the option to continue playing available instead.
However, according to the game's executive producer Casey Hudon, Mass Effect 3 will include a combination of both options. "It's probably going to be a combination of both," said Hudson. "We're going to have a version of the post-game state that you can go back to and finish more stuff, but then we'll have stuff you can loop back around and do in new game+. It's a hybrid of the two."
Mass Effect 3 will be launching at some point towards the end of this year. It will be releasing on PS3, Xbox 360 and PC for the first time in the franchises' history.
Source: Game Informer