There is a really insightful, thought provoking post on BLDGBLOG about how American politics, and politicians, are fixated on the notion that rural, small town America is the "real" America, and its values and problems are the ones that should be of greatest concern, whereas in reality the vast majority of Americans live in urban environments and the domestic problems of greatest importance to the nation are fundamentally urban. The well argued point of the piece is that knowing what it's like to live in an apartment New York City is far more relevant to knowing how to govern than is knowing what it's like to live on a ranch in remote Montana. One of the factoids cited by the post is that there are more World of Warcraft players in the United States than there are farmers.
The fact that there are more WoW players than farmers in the country, I think, speaks to a larger point. There are now far more people in the US that effectively make their livings, spend the majority of their leisure time, do most of their communicating & socializing, and consume most of their media in cyberspace than there are farmers (or firefighters, or doctors, or you name it). While these people are not a coherent demographic group, they share a lot of concerns, have more than a few values in common, and are effectively addressed in more or less the same way - put those things together and you have a group that politicians should court. As today's kids who are natives on Twitter, Club Penguin, Facebook, etc. grow into increased political activity they will become a powerful social force, and possibly a powerful voting block.