I guess that I sould have made it about fletchings on an arrow in a quiver on each man's back ; the quivers positioned so that each man could not see his own arrow. [&o] In any case, the only thing that the first two men have to go on is the color of the feathers that they can see in the hats on the other heads. The third man, the blind man, does not even have that (except by logic). He does not guess though, he knows the color of his own feather.

Edit- Brian posted while I was posting this and he is correct as far as he goes but is a bit off in the logic of the second man. The second man looks at the blind man first. In fact, he can be positioned so that he cannot see the first man. Why does he look at the blind man first?