Sky dimension

The Sky Dimension (otherwise known as the Skylands, Floating Island Dimension, Dream World or Heaven) is a work in progress by Notch. It "performs well, [but] looks ugly". The Sky Dimension was originally planned for the 1.8 Adventure Update but soon shown that it was a work in progress. In 1.9pre3, two new blocks were added suggesting that players will soon be able to travel to the sky dimension in game. With the speculation about The Ender, however, the Sky Dimension might be delayed longer, and the 1.9 portal blocks might lead there.

In a live webcast on the Swedish gaming site feber.se Notch revealed that the Sky Dimension would "probably be a dream world" and that when "you go to bed there is a certain chance that you get dragged into the dream world instead. Then you will be able to do it on purpose later on.."

History
The Sky Dimension was first announced after Notch played Spleef against a man with the twitter account named "Evil_Notch" (video is on twitter). It was probably made to be like a "heaven," because the nether was considered to be and act like a hell declared by the Evil Mojang team. The sky dimension was not completely confirmed until Notch released an update via Twitter stating: "And because PC Gamer made such a big deal of the sky dimension, I guess I'll have to finish it. Consider it confirmed."

The Mod-Enabled Version
Notch left data in for an early prototype of the sky dimension in Beta 1.6 and 1.7. Using various mods it is possible to access this currently unfinished version of the Sky Dimension.

In this version of the sky dimension it is always midday and it does not rain or snow (though cloud cover does appear as if it were raining). Although uncommon, it is possible to find Sugar cane, Redstone, Lapis Lazuli, and more rarely Diamond. Like the normal world, you can also find Dungeons. Iron, Coal, and Gold. The only mobs that currently spawn in the sky dimension are chickens and very rarely cows and pigs. Below the islands of the sky dimension is nothing but the void and a layer of clouds.

Trivia

 * If you select a map while in the unfinished version of the Sky Dimension, your game will display the saving chunks screen and crash, because the current implementation of maps can’t handle exposed sections of the void.
 * Maps work in the Sky Dimension in SMP.
 * The Sky Dimension is an inversion of The Nether, whereas the latter is a huge rock filled with air, the former is a huge sky filled with rock.
 * The Sky Dimension, similar to the Nether, has weather disabled.

Videos

 * Notch's Sky Dimension in Minecraft Beta 1.6.4
 * Notch's Sky Dimension in Minecraft Beta 1.6.4 - Exploring with Hot Air Balloons!