This is in response to a post in PLENK2010 claiming that PLE's are a web 2 phenomena.
My PLE predates web two. One classic component is the personal library, and of course our network of experts from whom we get topic specific advice.
What seems to have changed is the time constants.
Book v.s. blog post, a week vs 3 minutes.
A second issue is authority. As we become more exposed to polarised data sources, we become more sophisticated at reading the side chanell information which can indicate that the author is a kook!