The US PS Blog has confirmed that certain PlayStation Network functions are offline, and an update from SCEA's Patrick Seybold advises that it could last for a day or two.
"We are investigating the cause of the Network outage, we wanted to alert you that it may be a full day or two before we’re able to get the service completely back up and running," he wrote on the US PS Blog.
"Thank you very much for your patience while we work to resolve this matter. Please stay tuned to this space for more details, and we’ll update you again as soon as we can."
SCEE has updated the EU PS Blog with the same message.
The extent of the outage is not clear. Users have reported being unable to log into the PlayStation Network from consoles or web pages.