As you may have noticed in 0.5 damage indicator numbers were added to to some things when you hit them such as trees and buildings. This was a good start but is was not ideally what I wanted.
In the 0.5 version the numbers are drawn on the screen and not in the world. This makes them fine for damage that is caused by the players actions at the point they are looking at but not anything else. It also would not work for anything that did not have its own health bar (i.e. blocks).
In 0.6 this is changing, damage caused by the players actions will appear at the point of impact and show a number that floats up with the amount of damage caused.
Blocks in the world will also show how much damage was done to them as well as show their current and maximum health when looked at.
Every type of block in the world has its own max health as well as resistances to axes, picks, and shovels. Using the right type of tool will result in the full damage of the tool being dealt to the block while the wrong type will deal somewhere between 50% and 5% damage depending on the type of block.
From the small amount I have played with this it goes a long way toward giving the player real feedback about how their actions affect the world and it feels great.