Summary: Web and online communication and interaction is asynchronous. As such the delay, be it a matter of seconds or several days, disintegrates the sense of "being there" and "shared time" that characterizes co-presence, simultaneous, and spontaneous interaction. People have the time to consider themselves consciously, to tell rather than talk, and some of this comes out in online and social media as cold, distant, and self-oriented rather than other-oriented. And yet a great deal of talk now happens in a mediated fashion. The implications for the design of social software, online interaction, online community, and social media are significant. And they will become very interesting as these media become more synchronous.
We're obliged to return or at least acknowledge an incoming call or message. Or are we? What used to be common practice and courtesy would be downright maddening if it applied to all incoming messages. So we build conventions. In the case of asynchronous messaging technology, we face the unique challenge of not being able to acknowledge an incoming message without sending an additional message. To simply acknowledge a greeting, communication doubles. ("Wassup?" "Hey, got your message. Busy now but I,ll shit call you later when I have a min") Even the "I'm away from my desk" message included with IM applications begs to be customized. (What use is a machine apology? By definition, machines can't apologize...)
This fact of living with so many communications technologies is interesting insofar as it drives us to be explicit in our availability for interaction. There's no implicit way of signaling our current state of availability. Not knowing how a new communication technology works, we develop customs, practices, habits, and etiquettes. But these are constantly changing. (There was a time when Mom used to call to let me know she's sent or received an email.) Where's the appropriate burden of adaptation? With the designers and engineers, the UI experts, or the consumers?