Just a quick look into "Pleiadians, Nordic Aliens" just to figure out when people started to report encountering them. I can't find any report before the release of the movie "The day earth stood still" from 1951.
And even then, the two first notorious sources of encounters and information of them (Even the first to refer to them as Pleiadians and their origin from there) are Billy Meier and George Adamski. Now this is the big warning sign here for it. As for the more newer content and sources on it... Barbara Marciniak.
As for her. She claims they been talking through her for about 20 years now, to "enlighten" and lift humanity up before December 2012.
To be perfectly blunt. Pleiadians is most likely just some New Age mumbo-jumbo, and there is one extremly simple method to prove this. We all wait patiently untill January 2013 without doing or acting the crazy like following in the steps of "Heaven's Gate".
And let's not get into the subject of Alpha Draconians right now... It got even more big red blinking warning signs than Pleiadians got.
"Actually I would consider predator detection a major driving factor, being eaten has major disadvantages to spreading your genes." - Mattshark