Don't get me wrong. I think what Newsom did down in San Francisco kicks ass. And I'm not overtly worried about a gay marriage amendment; somehow, Reason will prevail. Hopefully.
No, what I'm more worried about are demographic polarizations. As more liberal areas (VT, MA, San Francisco) progress further while other areas lag behind, we may see a large demographic shift over the next few years as homosexuals across the nation (and there are many) emigrate to those areas, where they may have been more liberal on other issues and pulled their home states more towards the center.
For example: say there is a moderate (on other issues) gay couple living in Ohio (whose state legislature just instituted a gay marriage ban, if I recall correctly) decide to move to MA to get married (and more power to 'em!). But whereas the gay marriage issue might have tilted them Dem against Bush, they are no longer registered in Ohio.
Does anyone agree/disagree? Let me know if I've hit upon something potentially big or just ranting by the spectre of sleep at quarter-past three in the wee hours.