So it sounds like every time there is a decent-sized online community, media feels the need to plant somebody to repost content and engage in conversations? Is

So it sounds like every time there is a decent-sized online community, media feels the need to plant somebody to repost content and engage in conversations? Is this only done for Twitter and Facebook (and now Tumblr), or does this also apply to Orkut, Netlog, Bebo, MySpace, etc? And is this only applicable to social networks that are extremely communication oriented (vs. profile or media oriented)?