Nexus One Engineer Jeff Sharkey was experimenting with battery life in relation to the brightness and colour of the AMOLED screen, says Engadget. The Battery-saving effect is produced by switching off the sub-pixel LEDs in the screen. However, doing this can have some strange (yet colourful) results.
SurfaceFlinger effect modes on AndroidJeff Sharkey Tested a small rainbow of colours to detect which had the biggest effect on the battery life. He reports that on average, the red coloured screen used 42 percent less current than full colour. This almost doubles the battery life.
As of yet, the software that can drive this is not widely available - but could we see something like this in the future?
Sources:
EngadgetJeff Sharkey - This Link has all the tech specs