Halloween Update

Announcement
The Minecraft Halloween Update is planned by Notch to be released on October 31, 2010. The planned features to be released are:


 * A "Hell" world that can be used for quick travel, where you "portal in" walk ten meters and then "portal out" and you're hundreds of meters away
 * 1 new monster
 * More danger at deeper depths in-game
 * Torches that eventually burn out, but are re-lightable, and the introduction of lanterns as a new infinite light source
 * Fishing
 * 6 new block types (5 have unique abilities)
 * (Multiplayer) bug-fixes
 * Craftable Jack-O-Lanterns and pumpkin helmets
 * Craftable watch
 * Infinite fire source
 * A new dimension
 * And more. [See image]

This was announced on October 4th, 2010, and can be seen at minecraft.net/boo

On October 8th, 2010 a new type of block was announced. And on October 11th Notch wrote the following on his twitter: "I just made the most unfair mob ever even more unfair. You will hate the Ghast."

On October 19th, 2010 Notch added the following on his blog: "There are six new block types (five of them have unique abilities), one new monster, a new dimension, and a couple of bug fixes."

Media
No gameplay footage has been released yet, but there are some announcement videos and commentaries  here and  here.

On 10/10/10 Notch revealed the following screenshot on his blog: