During Gencon I had a thread in meta asking how long threads could go post wise. Well, as irony happened the thread got long asa few of us who didn't go to Gen Con just started posting like mad in there. That was the first thread like the Hivemind thread.
The name came from Piratecat or someone who said there was only really three people who ever used en world the rest of us were all part of Piratecat's mind, or a Hivemind. WE adopted the name and that they say is History.
REmeber, what can not be told what the Hivemind is, you have to experience it for yourself.