Valve has announced the second game add-on Portal 2 is in development and targeted for release early next year. The update includes an “easy-to-use,” in-game map editor so you can design, build and share single-player and co-op test chambers. The community will be able to view, play and vote on your creations with “a simple click.” The development of the editor was mentioned earlier this week with the release of part two of the Final Hours of Portal 2 app, but was unconfirmed at the time. Portal 2’s first content update, Peer Review, was released two weeks ago.