San Francisco 49ers quarterback Alex Smith, sidelined since Nov. 11 with a concussion, was cleared to play today against the New Orleans Saints in the Superdome, but Colin Kaepernick is the starter. It will be the second start for Kaepernick, the second-year player out of Nevada, who helped demolish the Chicago Bears Monday night, 32-7. Smith is the only other active quarterback Sunday so wide receiver Kyle Williams is the designated No. 3 quarterback. The 49ers also activated running back Brandon Jacobs, the former New York Giants star who will be available to play only his second game of the season.