The more that social networks pick up steam, the less influence blogging is receiving. Personal publishing is really exploding right now, indirectly, by people simply revealing their lives as content. Blogging is a much smaller piece of the pie. The web is better able to categorize everyones day-to-day ideas, in all forms of media, and thus these ideas have become more organized and useful for all.
Specifically, the dynamics of this influence coming from Facebook, Flickr and Linked-in-like communities is not very apparent. The overall influence or authority is for the most part, hidden. Maybe that's a good thing for now, while it lasts.