One of the things for us to note as database professionals about the Obama victory is that it has been incredibly data driven. Obama set new standards with his use of social media and data driven technology four years ago, and this year took it to new levels. Like it or not, this is the future of campaigning, and databases are going to be right at the centre of it. Databases often aren't seen as being all that sexy, but it's exciting for what we do to be at the heart of big events.
No. Obama, Romney, and 538 all implemented sampling. Some smarter than others. And it certainly isn't about relational databases. I interviewed to build one for one of the above, but they were more infatuated with Rails. Nuff said.