Nate Silver over at FiveThirtyEight has a really interesting piece up on divorce rates. In general divorce rates are down over the past decade, except in states that have bans on gay marriage or civil unions, where divorce rates are actually up. From the posting;
"Over the past decade or so, divorce has gradually become more uncommon in the United States. Since 2003, however, the decline in divorce rates has been largely confined to states which have not passed a state constitutional ban on gay marriage. These states saw their divorce rates decrease by an average of 8 percent between 2003 and 2008. States which had passed a same-sex marriage ban as of January 1, 2008, however, saw their divorce rates rise by about 1 percent over the same period."
The post has all the charts and data.