It has been in the news so much over the last day I'm sure you've heard about it (unless you're overseas). Obama has finally evolved. Not long after taking office he said his view on same-sex marriage is "evolving." Yesterday, he came out in full support. Yes, it is big news because this is the first president to do so.
We'll jump right past Fox News trumpeting that Obama has declared war on marriage and get to the interesting stuff.
There is belief that this will energize his base and reassure progressives leading to the election. An example of this is the $1 million in donations to Obama's campaign that poured in during the 90 minutes following the announcement. The gAyTM is open again. This will also (hopefully) be an impact on marriage referendums in Minnesota, Maine, Washington, and Maryland. Alas, the interview was the day after a big defeat in North Carolina (an article on the WNYC site explains how confusing that proposal was, no doubt intentionally so).
Rob Tisinai of Box Turtle Bulletin thinks Obama is a canny politician. Joe Biden, in an interview last Sunday, said he supports gay marriage. A day later, Arne Duncan of the Department of Education was specifically asked about gay marriage and also gave his support (alas, I didn't save links). The interviewer vowed to ask all cabinet secretaries until Obama himself spoke. But, Tisinai said, Obama used all that to drain his own statement of shock value to minimize blowback (though the Fundies were going to scream anyway). That implies Biden and Duncan said what they did because Obama asked them to.
Even so, this is great news. A gay kid can now dream, I can be president.
Andrew Belonsky of Towleroad says Obama's change in position could hurt him in seven battleground states. One of those is Florida, which has a much older population that tends to be more anti-gay.
The Guardian has a chart of gay rights by state.