I must say it's nice seeing some feedback on this idea. =)
Admittedly, I'm uncertain how the idea should ideally be implemented. Assuming the overworld is spinning, what would be its "face"? I'd imagine the simplest solution should be if the world's landmass is all one supercontinent akin to Pangaea.
Further elaboration on this idea would be changing the default skybox so the moon is no longer locked to the center of the night sky. Basing everything on a consistent lunar phase, it should technically be easy enough keeping everything in sync. I'm more than certain you already got insight into this, but for those who'd like a visual representation can check out this lunar phase simulator: http://astro.unl.edu/naap/lps/animations/lps.swf
But this feature will imply that the texture will change about 32 times during the lunar daytime. It will not be like the moon seen on the overworld: the moon needs to set in order to change its texture, while the overworld will change its texture every 2min30s on visible sky. I'm against? No, at all. I'm just warning that seeing the overworld changing its appearance in front of your eyes might be a little weird. But, hey, who will keep looking at the sky all the time?
Admittedly, I'm uncertain how the idea should ideally be implemented. Assuming the overworld is spinning, what would be its "face"? I'd imagine the simplest solution should be if the world's landmass is all one supercontinent akin to Pangaea.
Further elaboration on this idea would be changing the default skybox so the moon is no longer locked to the center of the night sky. Basing everything on a consistent lunar phase, it should technically be easy enough keeping everything in sync. I'm more than certain you already got insight into this, but for those who'd like a visual representation can check out this lunar phase simulator: http://astro.unl.edu/naap/lps/animations/lps.swf