I'm sure everyone will have their "huh?" moments (as people have commented on the recent Gursky sale) when reading this. But for me, there is a much more questionable entry on this list than Gursky. (I like Gursky myself.)
At any rate, it's pretty interesting to see that the only photographers with more than one (and exactly two, actually) photos on the list are Gursky, Sherman, Stieglitz and Weston.
P.S. I did search before I posted this, but I could not find a thread where this list was referenced already. Maybe my LF search fu is not up to snuff.