minecraft-java-editionminecraft-redstone
The redstone lamp is powered, it seems, because it is lit. Then the cobblestone block in the middle should be powered as well with the same logic, but it seems it is not powered because the redstone dust upon it is not.
Why?
The third couple of blocks shows that a powered cobblestone block should power redstone dust that is lying upon it.
The confusion lies in the fact that there are two different types of power a block can emit. These are sometimes referred to as strong and weak power.
Weak power is given to a block under the conditions mentioned in the question, by having wire on top of the block or pointing into it. This will unpower torches, extend pistons, play note blocks and turn on lamps & repeaters.
Strong power is given to a block by having a lever on it, a torch underneath it or a repeater pointing into it. In addition to the abilities weak power has, it will also power redstone dust in an adjacent block.
A Redstone Torch only powers all other blocks, except the block it's on.
(As long it is placed on a block, and the torch is sideways.)
There is no way to light the lamp with the torch in that position, due to the torches properties:
It will merely loop, then burn out.
Source: http://minecraft.gamepedia.com/Redstone_Torch and presonal experince.
Best Answer
I got an explanation in the #mincraft channel on freenode that redstone torches from the side only "soft powers" a block. Sufficient for a redstone lamp to be lit, but not to power redstone dust above it.
A redstone torch from below is on the other hand hard powering a block, also affecting the redstone dust.