Transparent LCDs is not a new technology. It was first released as a consumer product some years ago, and the scientists in Avatar used them extensively. Up until now, these LCDs were used mainly for marketing, but now Fujitsu took a step and used this double-sided transparent LCD for a mobile phone.
This prototype can be controlled from bot sides, and it has also new functions for double-sided touch. The color still needs to be fixed, but maybe one day your smartphone will be a transparent piece of glass