Super 8 "interactive teaser" included with Portal 2
From Big Download:
Super 8, the upcoming summer action movie from writer-director J.J. Abrams, makes a surprise appearance in the just released puzzle-shooter sequel Portal 2. Valve's game just unlocked for PC players via Steam and it contains a very interesting surprise. In the game's Extras section was a brief "interactive teaser" for Super 8.
The teaser, which uses the Source Engine, has your character on board the train that's the subject of the massive wreck in the first Super 8 teaser trailer. Just before the crash you can look around the train car and zoom in on some documents but that's about it. After the crash you then wander around the train wreckage until you get to the car that contains ... well, whatever is in the car that breaks out with a massive scream. The teaser then ends and sends you via Steam's browser to the Super 8 web site.
Here's a YouTube video capture of the game.