Portal 2 DLC. After a massive launch just over a week ago – Valve says Portal 2 is its "fastest-selling" release since Half-Life 2! – the famously generous developer has outlined what it's calling "Portal 2 DLC #1."
For the asking price of $0, DLC #1 will offer "new test chambers for players, leaderboards, challenge mode for single and multiplayer modes, and more." While free DLC on the Steam-powered PC and Mac platforms is nothing unusual coming from Valve, DLC #1 will notably be "free of charge" on Xbox 360 and PS3 as well. Of course, adding Steam to the PlayStation 3 release was always intended to allow for this scenario, and we can only imagine Microsoft didn't feel comfortable with the Xbox 360 being the sole platform charging for otherwise free content.
Portal 2 DLC #1 is "targeted" for release this summer; it's not clear if that estimate is Normal Time or Valve Time, so don't mark up your Stephen Merchant calendars just yet.