In the latest Technology Review, Jason Pontin talks about "a new phenomenon in social media called "microblogs": short electronic posts, sent to friends or to a more general community, that deliver some information about the sender."
Sending microblogs broadcasts, "I am here!" Reading microblogs satisfies the craving of many people to know the smallest details of the lives of people in whom they are interested. Already, new-media intellectuals have coined a term to describe the new social behavior they say microblogging encourages: they talk of "presence," a shorthand for the idea that by using such tools, we can enjoy an "always on" virtual omnipresence."
Two interesting things here. First, the metaphor of "presence" suggests users who are close enough to easily interact with little difficulty or friction. To me, it has overtones of connecting with people where they are, rather than meeting up with them in an abstracted virtual space. Second, the whole microblogging thing confirms, for the Nth time, that the most compelling thing about "always on" is that it offers the promise of always being connected to other people. As Jerry puts it, other people are the killer app.