You're presenting at a conference. You hook up your shiny new Macbook with Thunderbolt to the Thunderbolt-enabled projector and give a wonderful presentation. Unbeknownst to you, someone who had physical access to the projector and Inception software, now has a full dump of your RAM, including unencrypted passwords and keys.

If this was VGA or DVI, you have no reason to be suspicious. But with Thunderbolt, you can never be sure anymore.