I do believe that this is yet another new topic that somehow we have knowledge about. I swear, one could ask a question about the appropriate type of O-rings that should be used on aft cabin door handle seals on a Boeing 747-400. Someone here would know.
Scientist are now giving more attention to this phenomenon, it's called something like six degrees of separation.
(I try to google a good article about it , found this one, but didn't have time to read it, maybe someone would pitch in with a good article, wiki doesn't seems to be a good one)
They believe that areas of the brain communicate using this paradigm. It's very efficient, and of course computer networks are now studying this to develop better network algorithms and such.