White....

Canon did a whole scientific experiment to back this up.
The cooler the device, the less noise, and the truer the colours.
In fact Canon has a patent (pending/active/expired?) for this and they use it in their DSLR/lens advertisement.
And it actually makes a slight difference, let's say, when photographing Rally Races in the scorching Dakar, the lens is fine but internal chip's cannot work at their optimal.

But if the lens cover is lets say "blue hue", it won't really matter which colour you get, they will still be using the same lens cover and you will get filtration of light in the blue spectrum.

But remember these are small differences in way-out-there examples, whatever colour you choose with the N8 should be great (except Apple green its hideous)