Probably should have reinstalled Portal 2 last night. Whoops. The new, totally free "Peer Review" downloadable content is now available for PlayStation 3, PC, Mac, and Xbox 360 players.
This add-on expands the P-Body and Atlas adventure with another test track to get stuck in, plus a single-player and cooperative Challenge Mode.
To coincide with this launch, Valve has predictably dropped prices on the series. Portal 2 for $14.99 on Steam until October 6? I like your style, guys.