The late '60s have gotten a lot of play on the runways lately. Saint Laurent's Hedi Slimane receives a lot of the credit, but he doesn't own the era. Marc Jacobs had his own mod moment not too long ago. Earlier in his tenure at Calvin, Francisco Costa was less inclined to look backward, but these days it seems just about everybody is doing it. Retromania is one of the defining memes of our time, and not just in fashion. Could it be because of the warp speed at which designers are required to put together new collections?