Beta 1.0Working server-side inventory. And as a result of that, a whole pile of bugs and issues got fixed.
Made SMP servers save chunks way less often in most cases. Chunks don’t resave if they got saved in the last 30 seconds.
Moving too far away from a chest, or having it blow up, closes the inventory screen.
Introduced leaf decay again. It acts differently from before.
You can now throw eggs.
Throwing an egg has a chance of spawning a chicken.
Added super exclusive clan cloaks for Mojang
Beta 1.0_1Fixed double chest bug.
Fixed rare crash on level load bug.
Frame rate/performance issues not fully fixed .
Disconnects from multiplayer servers due to overflow.
Crashes after login on GNU/Linuxv
beta 1.0.2Fixed problem where game wouldn't run on Macs plus possibly other unknown fixes.
Beta 1.1Fixed “fancy” characters not working in the game by detaching font resources from the code.
Rewrote leaf decay.
Fixed FPS drops in single player.
Fixed players getting spammed with data and getting disconnected in SMP.
Fixed the item dupe bug in SMP.
A few special events happened on the following specific days (according to system time):
On the date of Christmas Eve to Boxing Day:
The quote on the main menu said, "Merry X-mas!"
All players wore a Christmas themed cape.
On the date of New Year's
Beta 1.1_01Added a missing font file in the package build.
Beta 1.1_02Fixed the chest not opening with empty hands bug.
Beta 1.2New addition charcoal
Note Blocks (right click to tune, trigger to play)
15 wool dyes
A new passive water-dwelling mob (Squid), which drops the new item Ink sac
New tree types (Birch, Pine)
Reeds retconned into sugar canes. They still make paper.
A bunch of new crafting recipes
One secret useful block (Dispenser)
One secret pretty block (Lapis Lazuli)
Sugar - Crafted from Sugar Cane
Default furnaces given new look
Bones added to the drop table, exclusively for skeleton archers.
Bones can be
Beta 1.2_01Fixed various blocks acting really weird when placed (rails, torches, and more)
Added a new painting that was not added in version 1.2
Reduced spawn rates a bit
Fixed a whole pile of lighting bugs
No more ghosts at night
Added a temporary fix to get rid of chunk visibility errors 
Splash text on the Main Menu returned to normal. (No longer constantly shows the quote "Finally beta!")
Slimes were re-added to the game with a very low spawn rate 
Beta 1.2_02Skins are now downloaded from Amazon S3 instead of minecraft.net
Lapis Lazuli Ore now drops 4 - 8 Lapis Lazuli per block mined (increased from 1) on single player only (Minecraft beta servers have not been affected yet).
Lapis Lazuli Ore can be found at bedrock level.
Ink Sacks have been re-named to "Ink Sacs".
Client/Launcher UpdateUpdates now voluntary
Official Links added
Community Links added
Command line support added
Twitter Links added
Ability to choose Minecraft directory location
Beta 1.3New blocks/items (Redstone Repeaters, Beds)
Added three new half-size blocks (Wooden Slab, Cobblestone Slab, Sandstone Slab)
Breaking a block made of two slabs now drops 2 slabs.
Slimes have a higher spawn rate
New Mojang logo splash screen
Graphics settings screen
Ability to toggle between classic lighting and "smooth" lighting
Worlds now use a generic McRegion chunk save format, with built-in auto conversion
While starting a new world, players can choose the world's name and seed to generate t
Beta 1.3_01Bug fixes:
Dependencies on Java 1.6 are gone
Fixed the recent issues on some Macs in which the game would crash when "Singleplayer" button was clicked on
Able to connect Client to Minecraft Server 1.3
Fixed item duplication glitch
Beta 1.4New Minecraft logo (no longer 3D blocks).
Added wolves that the player can tame, or kill for no loot.
Added Cookies which heal the player for 0.5 hearts.
Sleeping in a bed now resets your spawn position, though does not work for most users. Apparently, at the moment the spawn point unintentionally only changes if "Leave bed" is clicked and the function is limited to SMP.
Sneaking while climbing will hang on to the ladder, thus being a handy cave tool.
Spiders will no longer trample crops and
Beta 1.4_01Removed the April Fools' joke. However, the locked chests are still obtainable by inventory editing or SMP /give command. They will disappear after a while.
Beds now act as a respawn point as intended.
Although this has been fixed for most players, in certain cases the bed may still fail to save the default spawn point.
A glitch is present where using a pickaxe on a Mac could crash the game.
Beta 1.5Added Weather.
Added Statistics and Achievements.
New Items (Detector rail, Powered Rail, Birch and Pine/Spruce Saplings).
New Item Web. Cannot be found naturally.
SHIFT-clicking on something in a chest will immediately move the selected item(s) into your inventory and vice-versa.
Birch and Pine/Spruce trees now drop Birch and Pine/Spruce saplings, respectively.
Huge performance improvements for old and slow computers.
Crafting a ladder now produces 2 ladders.
If lightning strikes a pig, it beco
Beta 1.5_01Bug Fixes:
Blocks can now be placed on Snow.
Rain no longer goes through translucent blocks.
Light does not go through stair blocks anymore, however if you did this in a previous update, unless the stairs are destroyed or a block adjacent is built or destroyed it will still work.
Pumpkins are no longer worn backwards.
Pumpkin and Jack-O-Lantern inventory texture is now fixed. Before, it was backwards. However, all pumpkins and jack-o-lanterns that were placed on the map before the update are bac
Beta 1.5_02 (Server only update)Bug Fixes:
Game no longer crashes from "internal server error" created by bugs in 1.5_01's Server in SMP
Players no longer get the "dirt screen" when taking something out of the Crafting Table
Placing Rails in North/South direction, followed by placing a piece of rails on the side (and thus making a curve) results in no curve.
"Outside" rain sound still plays when under a glass shelter. In addition, Wolves under a glass roof during rain will be perpetually stuck in the "shaking" animat
Beta 1.6Added Nether support to multiplayer.
The client will ask minecraft.net if the current login is valid. If the server says “no”, a warning message appears in the client. You can still play the game even if this happens. 
Added craftable Maps.
Added Tall Grass in some biomes.
Mushrooms now spreads (very) slowly.
Added server property view-distance. Sets the radius of terrain updates (in chunks) to send to the players. Range 3-15, default 10.
Added Dead Shrubs in Deserts.
Beta 1.6.4Bug Fixes:
Attempted fix for CPU usage issue on singleplayer and multiplayer.
Sometimes when you open a world you can get stuck for a short time (about 0.10 seconds).
Entering and exiting the nether in SMP resets health bar, but not health.
Dropped tools, once picked up, disappear after first use . Also if you die your tools can suffer a similar fate. If you shift-transfer such a dropped tool into a chest and back in your inventory, it's like a new-crafted tool without uses.
Beta 1.6.2Bug Fixes:
Fixed new item duplication bug
The item duplication bug was not actually fixed; items placed in a furnace can still be taken out of a furnace and duplicated infinitely by right-clicking (although it appears the newly duplicated item will not function). Also, bug with cloned items being picked up after death wasn't fixed too.
When using a furnace and placing items into it, as soon as it's activated all items minus 1 are ejected and must be placed back in the furnace in order
Beta 1.6.3The renderer is now capped at 100 fps while there are chunks to be generated. The excess time will be spent generating chunks instead of rendering frames.
The “limit framerate” option now limits the game to 40 fps and will spend at least 10 ms per frame sleeping.
The “limit framerate” option has been reset to “off” for all players, enable it again if you want it.
2 blocks deep water doesn't prevent you from fall-damage anymore. You need at least 3 blocks deep water to fall in.
Fixed item bug when picking up an item with a full inventory causing this to happen
Beta 1.6.5Advanced OpenGL re-added. (Still with same Toggle bug as of 1.5)
Framerate cap can now be changed, with toggles of 40 FPS, 90 FPS and 200 FPS. Except for the 40 FPS setting, the framerate will only be capped when there are any chunk updates.
Improvements for slow and old computers.
Shift-clicking an item in the crafting window now only moves the crafted item into the player's inventory.
Version number no longer displayed while playing. Still visible on title screen and in F3
Beta 1.6.6Bonemeal can grow tall grass and flowers on grass blocks. 
Added Performance in Video Settings, Options Menu. Can be set to Max FPS, Balanced or Power saver.
Changed the material of glowstone from “glass” to “stone”. This means you need a pickaxe to get resources from it. This also means you can now place redstone, torches, levers,etc. on them.
Made Glowstone drop more loot (2-4 Glowstone Dust).
Made the recipe sizes for creating cloth blocks and glowstone blocks smaller (2x2 instead of 3x3).