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". It is now a confirmed update but the release date is not known.

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", since the "Evil Mojang" team declared the Nether to be "hell". 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 Datamined Version
Notch left data in for an early prototype of the sky dimension in Beta 1.6. Using a mod developed by 303 or a Bukkit plugin developed by robin0van0der0v you have access to 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). Sugar cane cannot be found normally, and although uncommon, it is possible to find Redstone, Lapis Lazuli, and more rarely Diamond. Like the normal world, you can also find Dungeons. The only mobs that currently spawn in the sky dimension are chickens. Below the islands of the sky dimension is nothing but the void and a layer of clouds.

Trivia

 * There is a mod with a similar premise as the sky dimension called the "Aether" mod. This mod actually adds new items, blocks, and mobs, unlike the somewhat boring official version. Notch has been questioned as to why he would not simply add the mod.
 * 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 via SMP

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!