When PSN got hacked, Sony Online Entertainment's servers were effected as well - even if they came up quickly and players of games like Everquest, Everquest 2 and Star Wars Galaxies could log in as usual while the PSN network stayed down. Today, SOE brought down their servers again - having, according to an official statement, found a security issue that needed to be fixed.
"We have had to take the SOE service down temporarily," the company writes on its website. "In the course of our investigation into the intrusion into our systems we have discovered an issue that warrants enough concern for us to take the service down effective immediately. We will provide an update later today (Monday)."
At the time of writing, there's been no other word from SOE - we'll update this news piece as soon as we know more.
Update: Turns out that the reason for the sudden outage was a lot worse than a simple security measure that needed fixing.