I came across a post on the Gentleman Gazette that lists the preppy history and style. It gives a list of preppy designers as well. It's worth a read.
Today, the term “preppy” is far looser and a term regularly used in high schools across North America and parts of Europe. It still describes a subculture, but that of a social circle of well brought up men and women who have adopted a manner of speech, vocabulary, dress, manners and etiquette that becomes an integral part of their lifestyle reflective of the traditions adopted from those historic upper-class Northeastern families.
Of course, the prep culture, or coastal culture as I like to call it is still very predominant in those regions, but it has spread into other areas and is often referred to as southern culture and now classic American culture, adopted by men and women in all of the fifty states, as well as abroad.