Also possible to get a heatmap of a keyboard to see what keys were pressed last. I've seen this attack carried out in a youtube video, where a hacker could log back into a kiosk terminal simply by grabbing the heat signature emitted from the last few keys pressed.
I mocked CSI's "enhance enhance enhance enhance ah we can see the face of the killer reflected in the dirty wheel nut of that truck driving past" for years but these techniques are amazing.
Edit: will SF now include matte contact lenses for people in secure areas?