According to Wikipedia, viral marketing is so named because of it's likeness to:
...self-replicating viral processes, analogous to the spread of pathological and computer viruses. It can be word-of-mouth delivered or enhanced by the network effects of the Internet.[1] Viral marketing is a marketing phenomenon that facilitates and encourages people to pass along a marketing message voluntarily.So, viral marketing is not spamming Facebook or Twitter. That's just bad advertising.
Viral marketing is not a press release you spam to all your friends.
Viral marketing is not a Youtube version of your company's 30 second TV spot.
Viral marketing is the creation of something worth passing on, that then gets (and pay attention because this is key) passed on.
In short: it ain't viral til it is.
A good example of viral marketing is the Pomegranate Phone. What makes it viral?Well, I heard about it because Dave said, "Hey Mike, check this out." And now I'm passing it on further on this blog. It's being spread, freely, by people not associated with the Pomegranate marketing team.
Oh, and here's the original site for the Pomegranate Phone: http://www.pomegranatephone.com/
Pass it on.