Minecraft 1.4 updates and shiz yo

F3+P will toggle the auto-pause when the window loses focus
F3+H will toggle detailed item descriptions
Fire spread will be affected by the difficulty.[1]
Modding API.[2][3][4]
Will be called "plugins".[5]
Rewriting Lighting engine.[6] Current engine has some bugs. (See Bug Fixes below.) ABOUT BLOODY TIME

Added a Command Block that that can run server commands when triggered by redstone, intended for adventure maps. This is amazing, and will probably be abused but too bad
No crafting recipe, only obtainable through /give[7][8]
Use @p to address the nearest player, @a for all players (where applicable) and @r for a random player[9][10][11]
Only OPs can create it in multiplayer if there isn't already one in the game.
Will operate in silent mode so it doesn't display commands in the chat window.[12]
Added a few commands for use with the redstone command block
/difficulty to change game difficulty[13]
/difficulty 0 = peaceful
/difficulty 1 = easy
/difficulty 2 = normal
/difficulty 3 = hard
Toggling PvP[14]
/spawnpoint to change spawnpoint per player (not the actual spawnpoint but more like an invisible bed)
/spawnpoint <player> <x> <y> <z>
/gamerule <gamerule> <true/false>
/gamerule doFireTick to change if the fire should spread
/gamerule doMobLoot to change if mobs should drop items
/gamerule doMobSpawning to change if mobs should naturally spawn
/gamerule doTileDrops to change if blocks should have drops (does not work for paintings)
/gamerule keepInventory to change if you should keep your items in your inventory if you die.
/gamerule mobGriefing to change if creepers and endermen should be able to change blocks.
/weather [clear | rain | thunder] <time> to change the weather
/help command improved

More features inside the Nether[15]
Added Wither skeletons.
1/5 spawns will be a regular skeleton.
Wither skeletons drop Wither skulls.
Used to build the Wither boss.
Improved Superflat spawning options[16]
Entities (such as Cows, Minecarts & Ghasts) will be able to travel through Nether Portals and End Portals.[17][18]
Entities will pass through instantly, but at a longer "cooldown".[19]
There are no restrictions, any entity at all can travel through the portals.[20]
Will allow fire burning entities like blazes to leave the nether and potentially burn things.[21]
Portals will teleport an Entity relative to where it entered.[22][23]
Added Wooden Button.
Can be activated by Arrows.
Added new potions:
Night Vision potion.
Invisibility potion.[24] yes pls
Now hides the nametag[25]
Mobs do not see you until you bump into them.
Turns mobs invisible too.
Improved villages and villagers to make them more self-aware[26]
You can now restore a desolate village or create a completely new village[27]

Added a "Work in progress" block. (AKA Beacon Block)
Can be right-clicked to reveal a GUI
Glows as bright as glowstone and casts a white light into the sky when on an assembled pyramid.
a 3x3 platform out of iron, gold, diamond and/or emerald blocks is the minimum size
additional layers with increasing size under that increase the reach of the effects
Each layer unlocks a new level of effects and increases the block's range by 8 blocks
You do not have to use only one block type for the pyramid, images have been released by members of the community showing multiple materials in one layer.
The minimum range is 16 blocks
Players within the blocks' range will be given the selected effects every 4 seconds
Changing a block's selection costs 1 emerald, diamond, gold ingot or iron ingot
The best configuration of blocks requires 164 blocks
Each block can only apply one effect at a time. If there are 4 complete layers of blocks, players can additionally choose between Regeneration or tier II of the previously chosen effect
Unlocked effects for each layer of blocks:
1: Speed and Haste
2: Resistance and Jump Boost
3: Strength
4: Regeneration and tier II of the other chosen effect

Chickens will be fed seeds to breed instead of wheat.[28]
Carrots used to control pigs.[29][30]
a Carrot with a Fishing Rod will be the crafting recipe.[31]
The pigs start slow but end up going about 5 blocks per second.[32]
Pigs with Saddles will now drop the saddle when killed.[33]
Sheep spawn egg can now spawn colored sheep.
At least two new mobs[34][35]
Wither Boss Mob.
Wither Skeleton Nether Mob.

Zombies can now pick up and equip items on the ground.[36]
Items that are picked up will have a 100% chance of dropping after dying.[37]
Zombies infect villagers now[38]
The villager is immediately turned into a zombie[39]
On Normal difficulty, there is a 50% chance of infection and on Hard difficulty there is a 100% chance of infection[40]
Infected baby villagers turn into baby zombies[41][42]
Baby zombies are 50% faster, don't age and don't burn up in the sun[43][44]
Infected villagers will turn in to villagers again if you throw a Splash Potion of Weakness at them and right click on them with a normal golden apple.[45]

Added armor and weapon support for mobs[46][47]
Skeletons and zombies now rarely carry and drop armor of all kinds, sometimes enchanted[48][49][50][51][52][53][54]
Monsters wearing headgear do not burn up in sunlight.[55]
Even baby zombies can wear armor[56][57][58]
Zombies now sometimes carry and drop swords or axes of all kinds, sometimes enchanted[59]
Skeletons now sometimes carry enchanted bows[60] but only on Normal and Hard difficulties, with higher chances on Hard[61]
Zombies and skeletons now only drop gear when they're wearing it, and even then its only a small chance of it getting dropped[62]

Villagers can now like and dislike you[63]
Villagers who dislike you will refuse to trade
Villagers will dislike you more for killing their friends or allowing them to die
Depending on how much villagers like you, they will start to offer you better trades[64]
Trades may be made permanent again or last shorter/longer

Added a new painting, which shows how to "craft" the Wither Boss.
Added Item Frames that allow you to display an item on the side of a block in a frame.[65]
Any item can be placed in the frame.[66]
Some items have special abilities while inside the frame:
A map in the Item Frame will display actual topographical features.[67]
A compass in the Item Frame will actually show direction.[68]
A clock in the Item Frame will actually show the time.[69]
Added flower pots.[70]
Saplings, Mushrooms, Flowers, Cactus, and Grass (includes Ferns and Shrubs) can be placed in a Flower Pot.[71]
Added Cobblestone Walls and a mossy variant[72]

The ability to dye leather armor different colors.[73]
16,777,216 potential colors.[74]
Put dyes and armor in the crafting grid to apply different dyes.
Item tooltip will then display "Dyed" in the right color.
Use a cauldron to wash the dye off of the armor.[75]
Wolf collars will be dyable.[76]
Added Corner Stairs.[77] [insert victory music here]
Added new Map functionality.
Maps will be clonable and sharable.[78]
Are now crafted as a close zoom scale and can be extended (zoomed out) by adding more paper[79]
Paintings no longer drop when clicking in creative.
Trapdoors can now be placed at the top or bottom of a block.[80]
Possibly Lecterns for book display and storage.[81][82]
Heads can be placed for decoration[83]
Skeleton, wither, zombie, player and creeper heads.
Can be placed in the same angles as signs.
Can be hung against walls.
Can be obtained as a relatively rare drop, from skeletons, creepers, zombies, and wither skeletons.

Added Carrots, Potatoes, Baked Potato, Poisonous Potato, and Golden Carrot.
Carrots and potatoes can now be found either in villages or growing in jungle biomes.[84]

Fix for "black areas" darkening random spots of maps for no apparent reason.[4][85]