I saw the Daily Show rerun last night. I hadn't realized that when Joe Biden said that he had no problem with gay marriage he said that he thought that there has been an enormous cultural change on the issue, and that fewer and fewer people are much bothered by it. I'm far too lazy too lazy to look up a transcript, but on being asked why this might be, Biden said something like "honestly, I think a lot of it has to do with Will and Grace."
TDS treated this as just another goofy thing spouted out by the goofy Biden, but I'm not sure why. He's probably right.
I've never seen more than a few minutes at a time of Will & Grace, because it seemed to me like kind of a crappy sitcom. But then again, crappy sitcoms can weild a non-negligible amount of cultural clout.
I don't think W&G is by any stretch the only explanation for changing attitudes towards same sex marriage, but a mainstream network TV show with gay characters who weren't mopey and totally not sexually active probably wasn't nothing, either.