Yes, it has been announced that Saw 2 is in the works. In fact, you can look below to see some of the new screens for the Saw II being done by Konami and Zombie Studios again. Oh, and due out this Autumn as well as the new film. Looks like another cash in for a yearly title to hit shelves.
While the below screens do nothing by improvements to the visuals of the game, and by the looks the game play, the proposed story (via. wikipedia) expands how the video game franchise said it would. By telling the story of characters that no longer, or have never appeared in the films. This time from the investigations of Detective Tapp's son. The son of Danny Glover's character from the film and if you played the first game, protagonist of Saw: The Videogame.
Looks like he is looking into what happened to his father, and for some reason this requires a life changing "game" for the character. Sounds a bit out of character for the "serial killer" Jigsaw, but I guess we'll have to wait and see.