I am afraid this one's gonna be tough, but I still hope to find out the guy's name. He walked the Dior Homme Spring 2011 Menswear Show. I even contacted Dior, but they say they do not disclose such information.

the easiest way to find a model is:

especially when you know the shows name,which is Dior,so-think logically,Diors shows are in Paris fashion week,so enter models.com - agencies showpackages for SS 2011 and start diggin through the Paris agencies list.

you'll find him for sure.