Matt Cutts does not come straight out and hammer the PayPerPost bloggers and company model but the article applies to their business model and many other bottom feeders out their.
I think once you review his writeup you will understand why many of the paid posts are really nothing more but attempts to game the search engines of which Google is going to penalize those sites that play these games.
I think it is important though to remember that nothing is wrong with being offered merchandise to review or being asked to do a site review on topics that your are knowledgeable about.
My review policy requires full disclosure within the post if I have been given merchandise for the review and vendors know up front that they have no guarantee of a positive review of their product. We also actually use the product or service for a minimum of 3 days before we write the review as well.
The approach Google is taking her is one that some will not like but I think once you read the example you will come to the conclusion that some of the sites that are writing reviews have no credibility whatsoever. [mattcutts.com]