This bug is similar to the villager crowding bug and is more visible in big villages.
Iron golems tend to walk around buildings, which were selected by villagers as their favorite (buildings stuffed with villagers), while other places of a village are Iron-golem-free.
I'm not sure, if this behavior is a bug in Iron golem AI or if Iron golems are supposed to be nearby villagers (who definitely have bugged AI). Anyway, I've decided to report this here.
I can provide screenshots if needed.
Tested on 1.4.4 server with 1.4.5 client. My village was created artificially by deporting villagers from naturally spawned willage. It has exactly 120 houses with 960 doors. Whole village is designed as a huge 37x37x37 cube.