Baseball (Bud Selig) will probably do nothing about it. The Players Association is the strongest union in the country and they will fight Bud Selig/owners in court to the very end if disciplilnary action is handed down. Donald Fehr and Gene Orza are two slimeballs. They feel the privacy issues concerning their players outweigh the health, legal and ethical issues.
Giambi admitted using steroids during the 2003 season when the exploratory testing program was initiated. Pretty much, whoever tested positive wasn't going to face disciplinary action anyways.