Update 2: 28/12/2014
PS4, PS3 and VITA are presently online. Intermittency may be experienced when accessing some network services. We will update you with any changes that may occur with the status of the network. If you would like to receive a notice when PSN is fully restored, be sure to follow the official PlayStation Twitter account and our support Twitter account, @AskPlayStation
Update 1: 28/12/2014
Sony just announced that the Playstation Network (PSN) is being fully restored after a second extended outage and a brief period online following the Christmas blackout caused by denial of service attacks.
These holidays have been far from smooth for Sony's Playstation Network with continued disruptions to the service since Christmas day.
Although the service had a brief reprieve after receiving denial of service attacks from hackers known as Lizard Squad, it was short lived and the PSN service is now offline again.
Four hours ago Sony acknowledged that there were issues with the online gaming service and stated that engineers were looking into the issues. Sony have since updated their blog with the following statement:
The video game industry has been experiencing high levels of traffic designed to disrupt connectivity and online gameplay. Multiple networks, including PSN, have been affected over the last 48 hours. PSN engineers are working hard to restore full network access and online gameplay as quickly as possible.
From time to time there may be disruptions in service due to surges in traffic, but our engineers will be working to restore service as quickly as possible.
If you received a PlayStation console over the holidays and have been unable to log onto the network, know that this problem is temporary and is not caused by your game console. Weâ€™ll continue to keep you posted on Twitter at @AskPlayStation and weâ€™ll update this post once the problems subside.
Thanks again for your patience.
As you can see the downtime seems to be linked to the recent DDOS attacks and there is no time frame for a return of the service.
We will keep you updated with any further developments.