The Colts official web site seems to point to LB Clint Session being the starter on the weak-side in 2009:

Session, entering his third season with the Colts, moved from strong-side to weak-side linebacker during the offseason, and he likely will enter the 2009 regular-season season as a starter for a young, talented linebacking corps. “This offseason, I just wanted to be in the best shape of my life, that I’ve been in so far,” Session said during the Colts’ offseason conditioning program at the Indiana Farm Bureau Football Center. “I just want to pick up on this game as fully as I can.”