Zombie siege

Sieges are an upcoming feature in Minecraft. The first part of the project was added in 12w07a. Zombies have a chance of coming into a village in packs and attacking the Villagers at night. Usually, a whole pack will concentrate on one door or villager. Villager breeding will keep the population up based on the number of houses there are. Villagers will occupy player created houses.

As of 12w08a, Villagers have Iron Golems to defend them from Zombies and other mobs. Iron Golems can naturally spawn near villages.

Currently, only these functions are known to be implemented to the game, but there may be more features in future updates.

Trivia

 * When a Zombie is attacking a Villager or door, it usually cannot detect you unless you attack him.
 * Zombies also attack Villager children.
 * Villagers themselves do not defend others or themselves at all.
 * Although Zombies are the only mob that attacks Villagers, Iron Golems still attack other hostile mobs.This is probably because they can be created by The Player to defend him, not a village, It could also mean that other mobs may lead sieges against villages.