Much of what we do online has obvious analogues in the past: E-mail and IM replace letters and face-to-face chatting. Blogging is personal pamphleteering. Skype is the new landline. Social networks let us map our real-life connections to the Web. It’s not surprising, then, that these new tools deliver obvious social utility—Facebook is the best way to get in touch with old friends, and instant messaging is the quickest way to collaborate with your colleagues across the country. Twitter is different. It’s not a faster or easier way of doing something you did in the past, unless you were one of those people who wrote short “quips” on bathroom stalls.