I guess it takes awhile, but you can now add bloggers as a legitimate source of information, at least according to the FTC:
The Federal Trade Commission...can go after bloggers - as well as the companies that compensate them - for any false claims or failure to disclose conflicts of interest.
So this will make bloggers, commenters, and those associated with providing "tainted" information even more responsible for their content. I would imagine having Google just push their pagerank status down a couple of notches would be enough to curb any kind of nefarious activities.
Maybe Google and the FTC can work out a deal here - the FTC tips Google off to "bad bloggers", Google drops their pagerank down, and requires the addition of a "few" FTC advertisements on the bad blog.