I think part of the reason Prop 8 failed is gays are the new incarnation of "the Bradley Effect" that some worried would hinder Obama's victory. In general, most Americans are beyond that now. But, when I was in the grocery store the afternoon of the election, I got this strange feeling that a relevant percentage of those suburban soccer moms with their kids in the shopping carts would say they support gay rights, but after the barrage of negative and untruthful ads about children being taught gay marriage in elementary school, paid for in great part by the Mormon church, end up voting for Prop 8. The Yes on 8 campaign also had a last minute TV and mailer campaign to the Black voters using the image of Barack Obama, although he was opposed to 8.
This was in addition to the endless amount of other TV commercials that 35 million dollars will buy. Check them out on YouTube...