I've written entries before about how elusive successful viral marketing is and what happens when you try to manufacture viral marketing, but Ochman may have hit it on the head.
Using viral marketing in isolation will fail because it's not a substitute for traditional marketing techniques.
Based on this, it seems that viral marketing isn't as inexpensive as many people had hoped.
While Ochman primarily deals with blogging, there's certainly a lesson in here for podcasters. I think it's becoming accepted now that organizations that intend to produce a podcast simply as an ongoing commercial for their products will be disappointed in their listenership. The alternative, however, is to use a podcast as a single tool in a larger campaign that invoves more traditional methods to not only get the attention of a greater number of people, but to hold it.