Stealth Marketing Unethical?

arsTechnica has an article about the FTC issue of a public statement coming out against so called "stealth marketing" where people participate in the marketing of a product on behalf of a company without being aware of the fact that it is a marketing effort. Essentially this is viral marketing used in what the FTC deems an unethical way. A consumer group called for them to investigate it, but they declined. This draws a very fine line from my perspective of what is considered ethical and what isn't. The arsTechnica post specifically references the Sony PSP site I listed a few days ago. I don't really see a problem with that. In some of the examples the FTC cited, I can see a possible conflict. But I would hate to see viral story sites fall into the unethical category. They aren't really asking people to do anything, it's more just a storyline people are following. No one believes everything they read online, as long as a site doesn't try to pass itself off as official, I don't see why it would be misleading in a harmful way.