How do you decide whether a technological development is significant or not? Here's a simple rule: if the mainstream media — as represented by, say, Daily Mail columnists — are baffled by, or contemptuous of, it then it's probably worth paying attention to.
Gephi is an interactive visualization and exploration platform for all kinds of networks and complex systems, dynamic and hierarchical graphs. Runs on Windows, Linux and Mac OS X. Gephi is open-source and free.