The Community Team Leader of the official PlayStation forum in Spain has informed PSN users of a scheduled maintenance where some PlayStation Servers will be interrupted for several hours. This will not be a complete shut off as not all servers are effected, details follow.
From next Tuesday 12th January at 17:00 until 2:00 Wednesday 13 January, PlayStation Network servers will will receive some minor maintenance. During that time some online services like the PSN/PC Stores may not be accessible, but accessing PSN accounts shouldn’t be a problem.
Perhaps this is some minor downtime to setup some of the foundations for the Premium Services or just some server updates. What do you speculate this maintenance could be for?
[Source]