Moon

What is the moon?
That big white block in the sky that glows. The moon is not visible when you render at a "small" or "tiny" distance The template does not change. It is unknown if you can make enough blocks to go high enough to the moon. Theories are that it's just there for decoration in the backround and can not be reached.

What happens during nightime?
Grass blocks or saplings do not grow in moonlight unless there is a torch or a light source near it. Redstone torches work also.

Mobs will spawn and will make the whole map dark unless there is torches placed around.

What about the mobs?
When the moon is up skeleton, creeper, slime, zombie and spider mobs will appear to attack the player. When the sun comes back up Skeletons and Zombie mobs will explode because of the sunlight and burn. Spider mobs will still be there but are peaceful mobs during the day. Creepers DO NOT go away and it is unknown what happens to slimes because they are so rare.

Trivia

 * The night time lasts 9 minutes, 10 if you count sunrise.
 * You can't see the moon if you have the small or tiny render distances.
 * The moon is 8 x 8 blocks.