"Mechanical pixels" is an interesting turn of phrase. To my mind, this is no more (or less) mechanical than when molecules are moved around in the IPS LCD display you're probably reading this on.
Nitpickery aside, this is cool stuff. It will be interesting for sure to see what the first real commercialisation of graphene will be. Somehow I think that display technology is sufficiently mature that it won't be the killer app?
