We've all played the game where you pick the name you'd have if you were a stripper, porn star, or soap-opera star. How much do you want to bet that all the cardinals have played the pope name game? I don't know how the game works (that's all part of the secret conclave business), but I'm guessing that first they pick their favorite Roman numeral, and then they find a papal name that will go with that number. Maybe Ratzinger loves the concept of "sweet XVI," and he looked through the list of past popes and saw that the last Benedict was numbered XV, so voila, he is Benedict XVI. Or maybe he loves eggs Benedict. (If he had more of a sweet tooth, he'd have gone with Pius.)
All those other disappointed also-rans probably picked out their pope names too, only to lose the election to Ratzinger. You'll start seeing those would-be pope names mentioned on the cardinals' blogs, mark my words.
And they should totally retire pope names when they've had an all-star. Who's gonna have the balls to be the next Pope John Paul?