<handing out degrees...>
There *is* a pretty nice tutorial by Bannor Bloodfist over on
the Learning Curve.
It's a bit more involved in that it uses the available day, day2night, night and night2day anims on the tiles to animate the change. Those anims are triggered by the day settings in the module and locked to the day/night cycle, regardless of frame length, which makes them pretty handy, actually :-)
<...he stole from a pretty cool place>