By RICHARD ROSENBLATT, AP Racing Writer 40 minutes ago Kentucky Derby winner Barbaro suffered another significant setback over the weekend, and his fight for survival may have reached a critical point. After Barbaro developed a deep abscess in his right hind foot, surgery was performed Saturday to insert two steel pins in a bone, one that was shattered but now healthy, to eliminate all weight bearing on the ailing foot. The procedure is a risky one, because it transfers more weight to the leg. If the bone were to break again, chief surgeon Dr. Dean Richardson said: "I think we'll...