Shawn Horcoff, currently of the Anaheim Ducks, has been suspended for violating NHL/NHLPA's performance-enhancing substance policy. You can read the entire policy here. Players are subject to a maximum of two no-notice tests each year.
Per the agreement, every NHL player will be subject to up to two "no-notice" tests every year, with at least one such test to be conducted on a team-wide basis. Players will be subject to "no-notice" testing at any time.
Twenty games is the mandated punishment for a first time violation of the policy.