[UPDATE] Everything seems to be running fine now. All services have green light on status.playstation.com in every country. If you're still having issues, please comment below.
While the last holiday season showed less problems, the new year starts slow for Sony's network services. They have confirmed a PSN outage that is being under inspection right now.
Every service on PSN on every system (PS3, PS Vita, PS4) is affected by that. No info on the reasons for the outage is given at the time of writing.
You can check the PSN status over at status.playstation.com, which is supported in many countries now.
JerriKoe - Game on!