I'm uncomfortable with the ethics around "conversational marketing." It's way too easy for bloggers and online community members to pass off paid-for advertising as personal opinion. And without clear ethical standards like in journalism, too many people are following the money.
The clearest example of this kind of sleazy advertising is Federated Media's people ready campaign for Microsoft. Remember the day when the phrase "people ready" started showing up in ads spouted by bloggers you read? All paid advertising. My respect for Michael Arrington, Om Malik, Fred Wilson, and Matt Marshall as citizen journalists went down a bit that day. I hope most of these folks just didn't think very carefully about their participation. Some recanted and FM's people ready site is now offline. An embarassment buried?
At least "people ready" showed up in clearly marked banner ads. What's scarier are when community members inject advertising in their blogs and forum posts without appropriate disclosure. Draper Fisher Jurvetson funded PayPerPost is a whole business walking this shaky ethical line. Publicis Modem is in the game, too, I just got spammed by "Tracy" who is "reaching out to me" to participate in a "viral international buzz campaign". Yuck. Even my Warcraft guild is infected by conversational marketing: a Federated Media contest for HP computers is driving buzz for those products on my guild's forums and in-game chat. It's irritating.
Of course, deceptive advertising works. Paying people to talk about your brand does increase brand awareness. But it makes me lose a little respect for the community members who shill for advertisers. It's not the worst thing someone could do, but it's a little tacky. Seeing people talk about HP computers in my game today felt like the day I saw the Green Card spam show up on Usenet. Advertising is fine. Deceptive advertising that pollutes our online communities is not.