Remember how the Portal 2 DLC was supposed to come out tomorrow? Surprise! Tuesday is the new Wednesday as far as Valve is concerned, since the free content is being rolled out a day early.

The DLC is entitled "Peer Review," and features more co-op hijinks with P-Body, Atlas, and GLaDOS. It also adds a single-player and co-op challenge mode along with associated leaderboards.

We'll have detailed impressions up later today, but while you're waiting, you can go get Peer Review for free on Xbox Live, PSN, PC, and Mac.