Well, pcs usually see it as the Great Wheel, but is that the true arrangement? Who knows, and how can you know? In 4e, we used the World Axis cosmology, but the setting is the same as my 3e (and 2e) campaign. Were the planes different, or was it just that planar theory had taken a turn in a different direction?
From a behind the curtain perspective, who cares how they're actually arranged, as long as they work for the campaign in play?
This is an interesting idea that I would love to see a pc get into one day, though- trying to find the truth about the nature, arrangement, and number of the planes.