Your grandchild: "Did people just sit there?"
I have to confess that I've shamelessly ripped the headline of this post, as well as the first quote, from a post on NRKbeta, but it all serves a larger purpose.
You see, NRKbeta brought my attention to this thought-provoking quote from an article by Douglas Adams, which, when I read it, was a bit like a missing piece of a jigsaw puzzle falling into place, as I've been thinking quite a bit about how people use social media, and how the way they use it defines their understanding of it recently. I'll return to those thoughts later, but, first, here's Adams:
During [the twentieth] century we have for the first time been dominated by non-interactive forms of entertainment: cinema, radio, recorded music and television. Before they came along all entertainment was interactive: theatre, music, sport—the performers and audience were there together, and even a respectfully silent audience exerted a powerful shaping presence on the unfolding of whatever drama they were there for. We didn’t need a special word for interactivity in the same way that we don’t (yet) need a special word for people with only one head.
I expect that history will show “normal” mainstream twentieth century media to be the aberration in all this. ‘Please, miss, you mean they could only just sit there and watch? They couldn’t do anything? Didn’t everybody feel terribly isolated or alienated or ignored?’
“Yes, child, that’s why they all went mad. Before the Restoration.”
“What was the Restoration again, please, miss?”
“The end of the twentieth century, child. When we started to get interactivity back.”

Which brings me to a quote from The Cluetrain Manifesto (2000), to my mind, the book that best describes how the (social) web has changed business as usual.
In fact, if we are to imagine how the world may look like a decade or two into the future, I think this might be the book professors in intellectual history will use to introduce their students to how the interactive web, or social media, changed people's mentality, the way they communicated, what they came to expect of the world etc. (that is, if the age of mass media isn't treated as just an insignificant aberration as Adams suggests):
In many ways, the Internet more resembles an ancient bazaar than it fits the business models companies try to impose on it. Millions have flocked to the net in an incredibly short time, not because it was user-friendly – it wasn't – but because it seemed to offer some intangible quality long missing in action from modern life.
In sharp contrast to the alienation wrought by homogenised broadcast media, sterilised mass 'culture', and the enforced anonymity of bureaucratic organisations, the Internet connected people to each other and provided a space in which the human voice would be rapidly rediscovered.
Though corporations insists on seeing it as one, the new marketplace is not necessarily a market at all. To its inhabitants, it is primarily a place in which all participants are audience to each other. The entertainment is not packaged; it is intrinsic.
Unlike the lockstep conformity imposed by television, advertising and corporate propaganda, the Net has given new legitimacy – and free rein – to play. Many of those drawn into this world find themselves exploring a freedom never before imagined: to indulge their curiosity, to debate, to disagree, to laugh at themselves, to compare visions, to learn, to create new art, new knowledge...
...or simply to communicate, as Global Voices co-founder Ethan Zuckerman's 'The history of digital community, in less than 7 minutes' (via Sambrook) so aptly shows we've been doing 'literally from the moment people started connecting computers to one another':
[youtube=http://www.youtube.com/watch?v=F7O4uMRADB8&w=425&h=355]