As an atheist, the news of Benedict XVI’s resignation is not of particular significance to me (though I will check to see how his resignation letter compares to Nixon’s). However, it does trigger one of the most unusual elections in the world – a Papal conclave.
The Washington Post have already published an excellent article on the machinations behind a Papal conclave, and how they have changed over time. I highly recommend you take a read. As they quote in the story:
Officially, Ratzinger’s selection was attributed to the will of God, a force not amenable to any empirical test that is in our power to conduct.
Which is really quite some claim to a mandate.