Do unto others as you would have them do unto you represents the prisoners dilemma and a good rule for civilization.
Have you guys heard of the prisoners dilemma? It basically involves two people in a prison and they can either cheat or cooperate. If both cheat, there's no reward. If both cooperate, the reward is less than had only one of you cooperated and the other cheated.
The best way to play, it's been found, is always to cooperate in the first round. Do unto him as you'd have him do unto you. And if he cooperates back, you cooperate back. Otherwise, cheat.
In larger society, I'd think that the golden rule functions as powerful social cohesion, replacing blood ties. One doesn't hurt family a family is you, genetically. But by the golden rule, you treat everyone as if they were you, as if they were family. Treating everyone fairly and equitably, as you would like to be treated, is how we can all get along.
What interests me most about the golden rule, individual hypocrisy aside, is who society deems protected by the golden rule. Are Jews protected under the golden rule? Muslims? Blacks? Retards? Comatose people? Fetuses? Zygotes?
How do we decide who is deserving of treatment that we'd treat ourselves with?