There's still a circle in your examples. The center is in the middle, where your squares meet. The radius is arbitrary so long as you can establish a direction around your center.

My point is that even though the objects of interest might not comprise a circle (they could be scattered marbles, for example), a circle is still used to determine their relative positions -- therefore clockwise/counterclockwise orientations.

This is a subjective projection of the circle. If you run the same problem while looking up from underneath your grid you will get different answers -- or looking at your grid sideways, for that matter. :)

Update: Just to clarify a bit. What we're really talking about is angular motion around an axis. A circle is just the projection straight down this axis.

Matt