Nice article on bicycling.com about how to dress properly for road riding, by Simon Mottram of Rapha:

http://sittingin.bicycling.com/2007/08/wear-it-well.html

Obviously that still doesn't explain why his own company offers black socks in its catalogue. I own a pair, very useful for winter training when they can be hidden away under overshoes and legwarmers or tights. Still it's a nice view of what should be observed while riding on the road for our cousins "in the colonies" as some Europeans refer to the Americas.