You can see the sun even at night if you go high enough

this is because the sun, moon and stars are a skybox meaning they are not affected by the terrain and live "outside" of the game for instance no matter how high you fly you will never touch it (more likely you will crash)- what im sayin is that the terrain only generates for a certain distance (render distance and a bit) after this the skybox is exposed it also occours when a chunk isnt rendered and you can see through the land. (im going on now but) the sun is always there just its UNDER the layer of bedrock (end of stream)

As I wrote in MC-3128 this is an intended behavior. It's important to see the sun and moon under you when you are playing a skyblock or skylands style map.

Is this still a concern in the current Minecraft version 1.6.4 / Launcher version 1.2.5 ? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.