I have long been a fan of Seth Godin (he's recently brought out a new book - Tribes); his latest blog / article hits the nail fairly on the head when it comes to previous marketing techniques and how the market place and peoples perceptions have changed in such a short space of time.

Going from selling door to door, to mass marketing to now permission based marketing.

"Social media's growth in the last three years, though, gives marketers an inkling that there may be something else going on. Sure, they can run spam ads on Facebook, but they don't work. Social media, it turns out, isn't about aggregating audiences so you can yell at them about the junk you want to sell.

Social media, in fact, is a basic human need, revealed digitally online. We want to be connected, to make a difference, to matter, to be missed. We want to belong, and yes, we want to be led."