Portal 2 DLC Coming Mid-September
Since Portal 2 was released, Valve has said that there will be free DLC, both single player and co-op, released in the Summer. Summer is nearly over, now, and Valve has been quiet on any details or firm release dates. That changed at Gamescom, however, and Kotaku has confirmed with Valve that the free DLC will be coming in mid-September.
There have been previous rumors about the DLC in the past, due to Ellen McLain, the voice actress for GLaDOS, reportedly being called in to record more voice work for "a Valve game". The DLC is supposed to come out for every platform, PC, Mac, Xbox 360, and PS3, and unlike the "free" Left 4 Dead 2 DLC, this will be free for every platform that Portal 2 is available on. Beyond that, very few details have been announced for the DLC, but Valve has said that the downloadable content will include "new test chambers for players, leaderboards, challenge mode for single and multiplayer modes, and more."
Having not played all of the co-op campaign, I may not be as thirsty for new Portal 2 content as others but I'm still excited for the DLC, especially for the "more" Valve mentioned. Hopefully this isn't the only DLC being released for Portal 2 so we can see a content lifespan as long as Left 4 Dead 2's.