PSN is known for not exactly being the most secure online service in the world- in fact, there have been an increasing amount of reports of late that individual accounts are being compromised. The problem is endemic, but it’s easy to address, too- basic security functionality, such as two step authentication (already available on competing services Xbox Live and Steam) would go a long way towards resolving the problem.
Hopefully, the introduction of this functionality means that the amount of individual and widespread hacks that PSN is still troubled by will go down over the coming weeks and months.
Source: Rheena.com