Just be conerned with the red pinstripe on the end..those designate "L" lenses.. There are a LOT of L lenses that are not white:
14mm f2.8 L, 16-35mm f2.8 L, 17-40 f4.0 L, 24mm f1.4 L, 35mm f1.4 L, 24-70mm f2.8 L, 24mm f3.5 TS L, 180mm f3.5 Macro L, 135mm 2.0 L, 200mm f2.8 L.. Notice that these are all fairly small lenses..
The white lenses are suppose to deflect the sun's rays more than the black lenses, for lenses that have a lot of surface mass...which are said to accumulate heat,..like a black top parking lot,...and that Canon says can cause the lenses to somehow affect the way the light passes through them.. I can't say for sure, but I wouldn't doubt it.. just touch the surface of a long Nikon lens vs a long Canon lens on a hot day.. Besides, Nikon has even introduced their line of white lenses as well...(but no body buys them)..
&,.....they also look more cool than do Nikon lenses.. [img]/ubbthreads/images/graemlins/wink.gif[/img]