Marketing shills
This Boston Globe article about blogs that shill products without disclosing their connections is an eye opener. I suspect that as underhanded SEO techniques become more obvious to Google, companies will move into this sort of hidden message marketing by paying bloggers to load up entries with fake testimonials for products they've never used.
Take a look at Jeff Cutler's old blog entries by scrolling down here. You see obvious keyword linking that jumps out like "Credit Cards" and "Funeral Flowers". Of course, Jeff doesn't think he's done anything wrong and the article closes with "In our opinion, paying bloggers is no different than Tiger Woods getting money to wear the Nike logo."
Of course there is an obvious difference: Tiger Woods actually uses Nike products. Also worth noting is that it may very well violate FTC guidelines. [via]