Gallas would make for an excellent signing for any team looking for a defender and if Moggi can get him on a free that would be sensational. He would be a brilliant replacement for Thuram and his ability to play at right or left back makes the prospect of acquiring his services that much more appealing. He shouldn't have any trouble settling in with a number of French internationals already plying their trade in Turin so if he doesn't extend his contract with Chelsea we should do everything possible to make him a Juventus player.
Just imagine a back four of Willy Sagnol, William Gallas, Fabio Cannavaro and Gianluca Zambrotta with Emerson and Patrick Vieira infront of them. Impenetrable.