Mainly, I was positively impressed by how well the websites could contribute to the elections, motivating people to vote through tools such as the "counting" and the voter registration in Facebook, the video with CEOs, Google Maps showing where to vote etc.
On the other hand, the fact that the Internet still reaches a very restricted demographic and that fewer Republicans use Internet compared to Democrats made this entire work to be a lot more about Obama than elections. I also wonder if the effect could have been similar with another candidate. It seems to me that Obama's charisma and the "change" message contributed significantly to mobilize people also through Internet.
They mentioned the challenges to scale this work internationally, but I think even locally the effectiveness will depend a lot on the candidate and the moment.