Ok, so I tried setting several obvious ones to "high" - still grey. Then I set them all to "high" and I got terrain.
Still the slightly messed up terrain graphics that I was seeing in windowed mode, but playable. Everthing else looks great on any setting, the interface, graphics, leaders, etc. are great. Speed appears good with the lower settings, too. If we could just get the graphics to work right/better (and work on lower settings :) ).
Still, runs great for a just-released game!!
Oh - specs for me:
Late 2008 MacBook Pro - 2.4 GHz Intel Core 2 Duo, 4GB RAM, 9400m/9600GT 256MB (I should check which I have set on right now!).