I've been thinking about the comment I made on Umaysay's and Kevin's posts, and they probably could use a little expanding.
Something I'd like to try to get at today (which I suspect is something we couldn't help but get at, whether I posted this or not) is not just the use or prevalence of networks over time, but the changing focus of networks over time, and the changing perception of networks. I suspect that the nature of the Internet relating to physical space -- that is, virtually "connecting" disparate physical points via physical terminals at those points -- makes the presence and use of networks obvious to the average person in a way that they never were before, even in pre-Internet satellite age (global telephone, television, shortwave, etc.). Internet applications are designed, sometimes explicitly, to show us those networks and allow us to take advantage of them in the most efficient way possible -- this was the whole point of Friendster, IIRC.
So is this all that's changed about our perception of networks in the last 10, 20, 50, 100 years? Is "network" just a new symbol for what we called "community" in the 1950's?