Kourtney, Khloe, and Kim Kardashian have all had some pretty impressive cleavage-bearing moments in their paparazzi-filled lives. Cleavage of both the breast and buttock variety, in fact. This sort of thing just seems to come with the territory of being a Kardashian.
(Perhaps it has something to do with Kim having the most photographed behind since JLo... and the most talked about boobs...