The Obama campaign purchased billboard ads -- inside the video game Burnout. Not only is the Burnout series one of my favorites (in short, the goal is to deliberately crash your car), but buying an ad inside a racing game is very smart. Unlike an adventure game or a first-person shooter where you might walk by a piece of scenery just once, in a racing game one billboard might be viewed thousands of times by a single gamer who might play on this particular race course hundreds of times.
There's also a subliminal side to video game advertising as well. Simply put, did you ever play Tetris for a long period of time and then found yourself trying visually piece together bathroom tiles and bricks? To this day, I'll hear a bit of unrelated music or a sound effect and I'll instantly be reminded of a video game I once played -- and exactly what I was doing in my life at the time when I played the game. Sense memory. Or maybe I'm insane. Anyway, gamers will remember this billboard and they'll remember the Obama branding.