Neat, but I don't think it will work on laptops.
On laptops I think that they will use the LED-backlit LCDs, and to save power will turn off the backlight on darker areas, or dim it.
For example, you can make a shade of gray with an LCD by either setting the LCD pixel to block half the light, or only shining half the light through it. Enormous power savings there without the user even noticing a difference.
Not to mention that LED backlights, even when full on, are going to use a bunch less power. Unfortunately, LCD screens with per-pixel LED backlights are VERY expensive.