Sounds like something with great potential for hackers to mess with:
* Change eInk highway speed signs to infinity symbols
* Play pong or breakout on the road by selectively updating the eInk strips
* Cause chaos by updating the road lanes every few seconds - now there's one lane, now there's three, now there's a statement: "Th1s r04d is 0wn3d by h4ck3rz!"
* Attach a video camera to the back of an eInk sign so it shows whatever is behind it. If the sign was using bright, colored eInk it would go invisible at the right angle.
-Mythago