Of Sockpuppets and Spouses
One of the political sites I read has installed software to try and block sock puppets.
A sockpuppet is a blog comment, wiki participant, or other online identity that exists to simulate discussion and agreement. For example, A Pundit writes a controversial opinion, and then logs in again as A Wise Reader and opines that his own post is brilliant.
If we regard blog comments and other social software as trivial playthings, then sock puppets really don't matter. As soon as we take them seriously, though, sock puppets matter a great deal. For example, sock puppets can unfairly boost (or decrease) karma rankings, product ratings, and other seemingly-democratic and open voting systems.
You might try to detect sock puppets through technical means, looking for multiple identities that share a common IP address. That's doomed, because members of the same household are also likely to share the same net connections. You might try to detect sock puppets stylistically, or through their posting patterns. But close friends and allies might well look like sock puppets to even the closest observer.
Can you distinguish a sock puppet from a spouse?