Unless you: a) have been living under a rock, or b) are a social conservative in deep, deep denial –
you will not find that headline a surprise. What is surprising is the degree of support that exists for gay marriage and (as many have pointed out before me) the incredible swiftness of the change.
As the accompanying graphs show, in only ten years, we've gone from a seventeen point margin against to an eighteen point margin for – a thirty-five point swing. And while there continues to be a huge difference in opinions by party affiliation, the trend line for Republicans is as the same as for Democrats and Independents.
Many more graphs and demographic breakdowns at the Pew site.