Doc Searls links to Mike Arrington, who's taken note of PayPerPost.com. Here's Mike's description:

Ted Murphy, CEO of advertising firm Mindcomet, has launched a new service called PayPerPost.com. You guessed it, it’s a marketplace for companies to connect with bloggers who are willing to blog about a product - for a price. The companies can set guidelines for their requests such as whether a picture must be included and whether they will only pay for positive blog coverage. There does not appear to be any requirement that the payment for coverage be disclosed. There is a requirement that PayPerPost.com must approve your post before you are paid. Wow.

This sounds like a blogosphere version of product placement. You know - you watch a movie, and when a laptop gets opened, it's a MacBook. When a soda gets drunk it's a coke. And so on. I'm not sure I'd call this the end of the blogosphere as we know it, but it sure will make separating the wheat from the chaff a lot harder.

Of course, you already need to pay attention to the messenger. I do Smalltalk advocacy here, and you should take note of the fact that I'm the product manager for Cincom Smalltalk. The relevant bit here is that I disclose that - and as Mike notes above, there's no apparent disclosure in the PayPerPost system. What this boils down to is that anyone using this service had better hope that they aren't found out - their stealth marketing will turn into an anti-campaign immediately.