Chang makes the point that social media need a more robust system of identity and reputation to support online interaction -- so that communities have ways to freeze out irresponsible and hateful individuals.
I think this is a particularly serious issue in countries like Korea and Japan. In these countries, where "real life" society is quite buttoned up, people turn to online forums to let off steam anonymously. For example, Japan's social networks (such as Mixi) tend to be anonymous and the most famous bulletin board, 2-channel is full of posts under the identity "No Name". Many Japanese people feel that this anonymity protects their privacy and liberates them to say what they really think.
I remember a conversation that I had a few months ago with a Japanese technology blogger who hides his "real life" identity. His technology blogging struck me as inoffensive (and brilliant), so I couldn't understand why he asks people to refrain from taking his photograph and why he dons a disguise before making a speech in public. (It sounds like a comedy about the mafia... right?) He told me that he feels a need to stay anonymous, even for his politically neutral blog.
I wonder if it will always be this way? I hope that more people in Japan will see the value of social media where online identities are associated with offline identities. That seems to be the surest way to ensure that people behave responsibly.
[On an unrelated note - I have heard that the email subscription software on this blog has been sending out multiple emails with the same information. I'm trying to get that fixed as soon as possible].