My thoughts on the first post-SHTF communities are similar to what Selco wrote, in that the first groups to emerge will be family based. Then I think you will see several family-based groups start to work together and at that point, a village or town will emerge from the ruins.
My belief for this kind of situation to be successful is that some kind of agreed-upon decision-making institution will be needed. I would guess that would look like some kind of council of elders with a senior representative from each of the major families in the village/town. This would probably work on small situations very well, like with a dozen family groups, but what happens when the town grows beyond that?