If you have seen The Avengers, you might have noticed a number of equipments or devices that has semi-transparent touch screen. Of course, they are enhanced by graphics in the show. Nevertheless, it seems that we are a step closer to making them in reality.
Check out this prototype from NTT DOCOMO and Fujitsu. It has a long resolution (320×240) 2.4-inches double-sided touch screen. Each side can work independently, according to the video.
Of course, it is still a prototype and I can bet that no one will buy such a low res screen nowadays. I still prefer this smart window.