Word of mouth is such a fast growing and expansive category of marketing, everybody is trying to lay a claim to what they are doing as word of mouth. I presume if it's ethical and legal, that is their "freedom of speech" rite.
However, as an expert and practitioner dealing exclusively in this space, I have to communicate order out this "frontier marketing" chaos. Emanuel Rosen, one of the best authors on the topic even has a tough time keeping it straight.
In order to make it more clear for the less initiated, particularly prospective clients, I have recently begun to simplify how I break down the various forms of word of mouth into five basic categories (although I love long lists as witnessed by my previous posts, based on George Miller's Cognitive Psychology work, the human brain can only store 7 +/- 2 different variables):
1) The Online WOM Variety - general audience participation, principally driven by the media and creativity - including viral ads, viral video, tagging, viral memes, alternative reality, advergaming, online voting/petitions, affiliate and mobile marketing (typical example - Honda Cog, Dove Campaign for Real Beauty, 42belowstories, Five Tag, March of Dimes petition, others)
2) The Offline WOM Variety - general audience participation, principally driven by the "live" event, novelty effect or impact media - brand experience, events, retail placement, stunts, guerrilla, pop ups and other forms of buzz marketing (typical example - KFC Logo from space, Absolut, American Express Front of the line, Ikea Openings)
3) Social WOM Media Driven - web universe participation, driven by interaction between sender, receiver and the community that surrounds them, including blogs, podcasts, wikis, web 2.0., social networks, social bookmarking, RSS and crowdsourcing (typical example - Second Life, GM - Fastlane, Daily Candy, 800CEOREAD, Amazon reviews )
4) Influencer WOM Driven - restricted audience participation, typically short term, driven by the knowledge, involvement or connections of the initial participants - including referral building, product seeding, beta testers, mystery shoppers, cause marketing, online research panels and coolhunting (typical example - technology, game or film launches)
5) Community WOM Driven - longer term and self-selected audience participation , typically online and offline, driven by the attachment, intimacy, affinity or reward derived by the attached brand, company, product, service or idea, including brand champion/evangelist/advocate programs, user groups, fan clubs, grassroots sponsorship, employee stakeholder programs, community forums and citizen advisory councils (typical example - Harley's HOGs, Running Room, Apple, Maker's Mark Ambassadors)