Shirky: Social Software and the Politics of Groups: "Social Software and the Politics of Groups
The thing that makes social software behave differently than other communications tools is that groups are entities in their own right. A group of people interacting with one another will exhibit behaviors that cannot be predicted by examining the individuals in isolation, peculiarly social effects like flaming and trolling or concerns about trust and reputation. This means that designing software for group-as-user is a problem that can't be attacked in the same way as designing a word processor or a graphics tool.