Are Personal Learning Networks a modern entity?

Hi there. This will be a short post as I've spent all night trying to work out how to use Adobe's Contribute to edit my blog only to figure out that it is much easier to do it online. Maybe I'll figure that out at some point in the future.
Well I'm enjoying what I'm reading so far. The "7 things you should know..." peaked my interest immediately. The idea that an individual creates their own network of peers, experts and resources in order to follow their own particular interest is fascinating.
I wonder for how long they have actually been occurring outside of formal education. It seems to me that an individual would probably have developed a PLN as they try and learn about any undertaking. I try to paint every so often and I get better at it by asking people for suggestions or criticism about what I do. The people I ask are students, art teachers, my peers, my sister (who is a graphic designer), and others. I have books of my own and borrow from the local libraries as well. I have occasionally used the web to find forums or watch videos.
My point is that PLN's have probably always existed in some form or another for as long as people have tried to improve their skills by developing a network of experts, peers and resources. The addition of technology into this mix has just broadened the distance between the individual nodes of the network. I can ask my sister in the UK just as easily as one of the art teachers in my school. The Internet wasn't available 100 years ago, but the ability to network certainly was.
From that point of view, maybe the idea that PLN's are an effective tool for education won't be that hard a sell. The issue would be to show how this potentially open-ended and unstructured system would lend itself to the assessment of required outcomes for students.
.....added later (found comment in similar vein in discussion on Moodle)
Some questions:
How applicable do people see this in high school or primary school settings?
How do people envisage assessment occurring?
Would assessment be a case of submitting pieces of work, or would it be a case of gradually developing and quantifying the respect of your peers as you progress from novice toward expert in your particular interest area?