Iron Golem Factories are... Iron Golem Factories! They spawn around NPC villages, using pistons and redstone to move pumpkin heads onto Iron Golem bodies. The Iron and pumpkin supply replenishes every 3 Minecraft days in a default world type, but only once every Minecraft week in a Superflat world.====How they work====
Redstone Wire connects pistons to levers, and the pistons move pumpkins onto Iron Golem Bodies.
====Why this should be added to Minecraft===
Because they are instrumental to the Cyborg mob, as well as a good source of protection for NPC villages and a good source of Iron for the player. They are also the first Generated structure to use piston and redstone mechanics. However, in the player-made Iron Golem Factory shown in the pictures, the pumpkins are actually broken when the lever is pulled, meaning that pumpkins would have to be slightly modified in order for this to be added. But honestly, in what parallel universe is that not worth it?