I saw a documentary about Charlie Chaplin. This was happening to him back in his day. This has probably been going on since we've had culture.
You know, I just had a weird connection when you mentioned that - I'm reminded of one of the early scenes to 2001: A Space Odyssey... The "dawn of man" scene. Link posted below for reference.
http://www.youtube.com/watch?v=m2XcPNSeUMQ
One ape wakes up and notices the monolith, starts to make a little noise. This in turn wakes up the rest of the apes and they start to make more noise, their tribe is running quite wild.
Eventually one starts to try and interact with the object, soon more follow and learn from it.
If you think about it, this is pretty much the essence of web 2.0
http://delicious.com/ (half the links were chrome related)
It doesn't seem to be limited to any particular "group" of people either.
The same thing happens here on HN aswell to a smaller extent & I fully expect to get modded down to all heck because of this comparison.
To me, wisdom of the crowds is abit of a misnomer, as once there is an original "acceptance" by a small group of people, the web 2.0 echo chamber kicks in.
This kind of effect is not just limited to social news sites either, the exact same thing happens with blogs aswell - eg, a story might appear on Techcrunch, and then 1000 "me too" posts will pop up around the place.