Social networking is nothing new really; we've always been doing it. We've just not had such powerful tools to help us as we do now. In the past I could write this and send it as a letter to a friend, who could in turn quote me to several friends and so on. The great thinkers of old networked intensively sending vast amounts of letters to colleagues around the country and even abroad. That's how ideas spread; slowly but surely.
There's a great video on this theme from Stanford University that I paste in here showing how many of the great names of the 18th century such as Darwin networked (evidently Darwin sent over 15,000 letters in his career). It's easy to draw the conclusion that these people would have been able to achieve much more if they had the instant mass communication we use today. However, maybe the slow method had some advantages; more time to formulate your ideas, more time for your colleagues to read and assimilate them, more time to think more deeply. Read more on this video on the blog post Networks and the information glut.
There's no doubt that today's ideas spread instantly and to a mass audience. Academic discussion was previously the domain of a privileged few whereas now anyone can access the thoughts of the experts. One major difference between the two approaches is that Darwin's correspondence is still there for us to read whereas much of today's correspondence is rather emphemeral and may be very difficult to trace in 100 years from now. What price The Collected Tweets of Charles Darwin?