For example, for a Nine Inch Nails album release, they planted a thumb drive with an unreleased track in a bathroom at a concert. A fan found it and posted it online, and other fans performed spectrographic analysis on it to find a NIN image embedded in the static. That led to websites purportedly sent back from the future (with warnings from the fictitious "US Bureau of Morality") and a whole intricate puzzle story about the rise of an authoritatian anti-art government coming to power. The game recruited fans into a "resistance movement" against the anti-art future goverment. One creative element was that when the CD's were released they were heat sensitive to reveal text on the disc surface after being played. The game ultimately ending with some fans attending a secret NIN concert.
You can see some of their case studies here on the 42 Entertainment website. In another game, to promote Batman Dark Knight, one part of the game had fans go to a real bakery to pick up a cake under a false name. The cake had a ringing phone in it, which was then used to provide directions over the rest of the game.
The Twitter tag for the conference was #MITBig