peevee1: They should have higher resolution in Green, not in blue. Only about 5% of cones in our eyes are responsive to blue light. We are adopted to see detail in green foliage, not in a blue sky.
The arrangement has to do with the absorption of colors of the spectrum according to their wavelength as they pass through the silicon wafer. Blue color penetrates the least so it´s on top of the sensor stack, the red color penetrates the most so it´s on the bottom of the stack. Please, see http://en.wikipedia.org/wiki/File:Absorption-X3.png