A while ago I posted the story of a student film project using agile practices to create a documentary. One interesting observation made by the instructor is that trust among the group developed in an interesting fashion.
At first, the group self-organized by try to work in groups of three. However, when plans were made to get together (for example to film an interview), often, one of the three people would cancel. Probably, that person considered two people to be enough to do the work.
After noticing this pattern, the group decided to perform work in pairs. This made the commitment to working much stronger and eventually led to a more trusting work relationship.
I have also observed this pattern in other situations. Pair programming, pair writing, pair designing, pair problem-solving… all of these behaviors seem to arise naturally in a self-organizing team.