Promising new poll numbers out yesterday. According to a Field Poll, 51% of likely California voters plan to vote "no" on Proposition 8. 42% plan to vote to write discrimination into the California Constitution and 7% are undecided.
Remember, though, that on Proposition 22, the most recent vote on marriage equality in the state, polls showed the measure barely winning and it ended up taking 61% of the vote. Bigots, it is not surprising, tend to lie about their bigotry to pollsters.
More analysis here. What you'll see in that breakdown of numbers is that every age group opposes Prop 8.