Though it's no huge shock to find out what's behind Esquire's recent E-Ink cover, it's always fun to look at the postmortem pics. Phil over at MAKE took the magazine cover apart, and in addition to the E-Ink display, found lithium cells, printed circuit boards, and flash-programmable microcontrollers, which could be partially hacked or reprogrammed.
The E-Ink panel is segmented (11 on top, 3 on bottom), which means you can't use the entire rectangle for display. While you can change the timing for each section's blinking, the potential for real customization seems limited. Instead you could only change when each section blinks or doesn't blink (not much fun, I know).