Yeah I saw it a few years ago but it wasn't as flexible, it looked pretty cool, I think they said it would be done in a few years as well, so I'm presuming costs is the problem at the mo. In case you cared I also recently read an article that the see-through screens, as in minority report, will soon be seen.
Well I would presume it is because it takes time for the heat to be conducted/convected into the hand and that is why you have to leave it in there for an, all be it small, amount of time, i.e it takes a while for your hand to heat up and burn/cook, as does your food.