Not only is there momentum, but there's also demographics. Gay marriage has much more support by younger voters than older voters. Four years is enough to make a huge difference in this regard, as older voters die off and younger people become voters (or, if voting age already, become more consistent voters).
Thus, in November 2012, I think it's a pretty good bet that the voters of California will vote for same-sex marriage. They voted down same-sex marriage in 2008 by only 4 points. In 2012, they'll probably vote in favor of same-sex marriage by a small, but definite margin. Prop 8 will be history. Assuming a normal appeals process, involving a panel of the Ninth Circuit, an en banc review by the Ninth Circuit, then a certiorari petition to the Supreme Court, followed by briefing and argument, I just can't imagine the Supreme Court deciding before November 2012.
2 hours ago