Sony are taking the security problems and hacking on PSN very seriously and the service is still off-line for the time being. The Japanese corporate giant has confirmed during the weekend that the problems are due to external breaches of the security and they are now working around the clock to sort the problems and to make sure similar problems will not surface again.
Any time something like this happens it's unfortunate, but the timing with games like Portal 2, Mortal Kombat and Socom 4: Special Forces just released makes matters even worse.
The hacker group Anonymous has said they are not involved in this attack, and according to PCWorld Sony are still assessing the damage caused.
Hopefully, these problems can be resolved quickly and the service return to normal.