Ross Mayfield begins a blog on using wikis for team building with a quote from Socialtext CEO Eugene Lee:

Every time there is a new team member, it’s a new team.

This is a great mantra for understanding the dynamics of social networks. It’s easy to forget how the simple addition of one or two relationships can alter all the dynamics of a community or a network*. The structure changes slightly, but the collective changes in purpose, style, and value.

*Here’s a paraphrased quote from Dave Weinberger’s talk at Community 2.0. “A community is a network in which people care about each other more than they have to.”