As usual, every one is just copy pasting everything from notch blog, without actually giving a lot of info on it.
Seeing as how the original plan for the 'Adventure update" was taking too long, and had too much work, the decided to split the two up into two updates. 1.7 would be known as Jeb's update, and the 1.8 will be known as the adventure update.
1.7
Initial Release
New Features:
- Pistons
- Shears
- TNT now needs either fire, or a redstone current in order to be lit
- Silverfish
- Stackable fences
- New Brick and Cobblestone textures
- The F3 screen shows which direction you are facing using 0, 1, 2 and 3
New Bugs:
- Right clicking on a sheep while holding nothing would crash the game
- Using a piston to try and move Water, Lava, any plant that grows (besides trees) and other transparent blocks besides Glass would crash the game.
PISTONS

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Pistons can push any block besides obsidian and bedrock that is touching them in any direction, including the player.
Pistons can push up to 12 blocks at a time.
Pistons can be used to stop water flow.
Pistons can move other pistons, so long as the other piston is not extended.
If a piston pushes ice, it will turn the ice into water and the piston will disappear. It will reappear when it is retracted.
SHEARS
Shears are the only way to get Wool from a Sheep without killing it.
Shears can be used to 'shear' leaf blocks to be able to pick them up.
Shears can be used to break placed Wool blocks much faster, without damaging the Shears.
Shears are the only tool in the game to be possible to make in the player's 2x2 inventory crafting area.
FENCES
Fences can now be placed on top of other fences, without having to place a block, then a fence, then remove the block, then another fence. They can be stacked on top of one another just like any other block in the game.
Torches can now be placed directly on fences.
SILVERFISH
Silverfish.png was added into the mobs folder in minecraft.jar, and will either be used for the planned new mob in the 1.8, or for real fish that swim in the ocean.
1.7_01
Bug Fixes
Bug Fixes:
- Fixed right clicking on sheep without anything in the players hands crashing the game
- Fixed pistons crashing when trying to move transparent blocks
New Bugs:
- Right clicking on a sheep with an item in the players hand will make the item disappear. Shears are not effected.
- Certain blocks such as Doors and Obsidian will have pink particles
- If a pressure plate is on top of a block that is touching a piston, standing on the plate will crash the game.