http://www.joystiq.com/2007/10/02/im...ins-situation/

person impersonating an SCEA IT employee apparently weaseled their way through customer service and into getting unauthorized access to two PSN user accounts. The situation was discovered very soon after and access was disabled, with both account holders being notified. Kimberly Otzman of Sony's Corporate Communications said, "No consumer experienced any financial loss or damage. In response to the incident, SCEA immediately enhanced its customer service protocol, implementing additional security safeguards, and began an intensive investigation of the incident that remains ongoing."

Sony doesn't perceive this as a "security breach" as it was not attributed to a hacker and there was no electronic breach, just a person who slickly got access to the accounts through customer service.