WOW yess I totally Think that The Compass is ESSENTIAL.
Since the world up (in the maya plug i read) is Y up not Z neg the whole physical sun system is just a series of guess and check process so far. Im not sure wich way is which. Physical sky is great renders but i just have no idea where the sun is shining from until i render a few times.
Something simple like a curve or a simple stretched polygon triangle to represent North would just save lots of click and renders.
Plus a way to Visualise where the sun is too would be even better so a poly triangle to represent north and a poly cone to show the position of the sun. This would be my Number 1 request for the next Maxwel release.