It isn't just Twitter.
The great paradox of "social networking" is that it uses narcissism as the glue for "community." Being online means being alone, and being in an online community means being alone together. The community is purely symbolic, a pixellated simulation conjured up by software to feed the modern self's bottomless hunger. Hunger for what? For verification of its existence? No, not even that. For verification that it has a role to play. As I walk down the street with thin white cords hanging from my ears, as I look at the display of khakis in the window of the Gap, as I sit in a Starbucks sipping a chai served up by a barista, I can't quite bring myself to believe that I'm real. But if I send out to a theoretical audience of my peers 140 characters of text saying that I'm walking down the street, looking in a shop window, drinking tea, suddenly I become real. I have a voice. I exist, if only as a symbol speaking of symbols to other symbols.
H/T Andrew Sullivan