Kotaku: Players of the original Mass Effect had a big impact on the story of the second, if they imported their character save from the first game. BioWare imported some 700 player choices and associated plot points into Mass Effect 2.
BioWare lead cinematic designer Armando Troisi said during today's Mass Effect 2 Game Developers Conference session that it was "the small things" that mattered when carrying over player data from the original Xbox 360 and PC sci-fi role-playing game.