From Minecraft Wiki
March 13, 2014
14w11a is the seventeenth snapshot released for 1.8.
- Added Endermite.
- Appearance is similar to a silverfish's appearance, except they are purple and emit ender particles.
- Endermen are hostile towards them.
- Will sometimes spawn in place of an Enderman teleporting away.
- Will despawn after 2 minutes.
- Will spawn with a 5 percent chance when an Ender pearl lands.
- Not yet completed - endermites may have something to do with dragon eggs 
- Model will be changed in the next Snapshot 
- Added Endermite.
- Changed minecart physics
- Minecarts now go faster and farther
- Improved collision and position handling
- Minecarts can derail at corners if going too fast, as well as refuse to go uphill
- They now give a much greater boost to other minecarts
- When powered, they can move on non-powered rails without decelerating
- Minecart with TNT explosions no longer stack.
- Show two holes in their item icon.
- Silverfish will stop occasionally before moving again (similar to most mobs)
- Slimes seem to jump a bit more randomly
- Witches, skeletons, zombies, zombie pigmen and creepers now run away from exploding creepers
- Endermen walk slightly faster
- On the right hand side, a display shows up if you are looking at a block, giving various pieces of information and NBT data about it.
- Looking at a door and redstone shows you the state of the block
- Door: which way it is facing, if it is open, which half you are looking at, if it is powered, and what side the hinge is
- Redstone: power direction (up, down, side, none) for all compass directions (north, south, east, west) and power level
- Not 100% complete, data for a lot of blocks still missing
- Now internally use states instead of metadata
- Metadata will still be used for a while
- Block states of the block being looked at will now be displayed on the F3 menu - Examples: redstone, door
- Internally, metadata no longer needs to be calculated out of the 4 bit data value, instead the values of specified properties can now be easily gotten and set
- Block models
- Converted fence gates, brewing stands
- Lighting now works with models (most models for some users)
- Dropped items now face the player in all three directions on fast graphics
Pictures of fix to in block faces 
From released versions before 1.8
- MC-36822 – Minecart with command block merging
From the 1.8 snapshots
From the previous snapshot
- MC-50452 – Rails don't render from below
- MC-50838 – Entity UUID WitherSkull
- MC-50904 – ender man acting weird