I tested this with a static Assimp build and it doesn't want me to link ZLib statically, maybe it's just because OgreAssimp is not using it atm?
I'll boot into Windows and see what kind of trouble that'll bring.
Pushed a commit which changes the find assimp script to check against assimp/config.h instead of assimp/assimp.h - thanks.
The CMake script might be failing in places, but I am not too unhappy about it: at least they have chosen to use CMake, and it seems to work (ish).
It just needs some more love.
I might issue a pull request later on.
I shouldn't complain about things breaking in a 'master' branch - I can't resist, though..