According to Mepps, DCUO Community Manager, all servers were taken offline immediately to resolve a technical issue. Today’s downtime has been extended for all servers, for additional 4 hours, until around 5:00PM PST. We will update this thread when more information is available.
Update: All servers are now online.
Players may notice the following changes:
The feats for winning x number of lair battles have been updated so that the count increases when you win a round in a lair battle as opposed to winning the entire lair battle.
Fixed an issue that prevented players with a CR over 100 from receiving or consuming Marks & Treasure Boxes.
Fixed an issue that was causing Lair Battles to crash.
The Checkmate and Knight style items are now available on the PvP Appearance vendors in Watchtower and Hall of Doom for players with access to the DLC4 Last Laugh.
Source: DCUO forums