SOE hasn't announced an official release date beyond fall 2013, but the firm's new press release does detail what looks to be a pretty meaty update. New legends PvP characters Cheetah and Donna Troy are in the works, as is a new shared zone (Gotham City wasteland) featuring daily solo quests. A new alert and three new duo instances are also coming along with new gear and the requisite feats and collections.
Sons of Trigon will be free for Legendary members. Premium and F2P players can purchase it via the in-game marketplace, the PlayStation Network, or the DCUO website.
[Source: SOE press release]