Social Networks

Just came across a very interesting Wikipedia article on Social Networks, which links to a startling applet that models networks. I'm more interested in social networks from the perspective of a software ecology, in other words - how does this file deployed in a running system relate to the source code held in our Version Management tool over here? What dependencies are there between one object and other, and which are weaker or stronger? Can we refactor this code without impacting that code over there? And so on, and so on.