Most of us have known this for a while and eMarketer gives us new ammunition when making our point: Word-of-Mouth Marketing is the most efficient way to communicate with prospective consumers.
"More and more, consumers are relying on advice from friends, family and even strangers to make purchase decisions, select physicians, choose travel destinations and pick politicians to vote for. And many of them are giving — and getting — that advice online."
eMarketers estimates over 25 million US adults regularly share advice on products or services online.
I believe eMarketer should have included communities as well. Social Networks/Groups/Communities/Whatever you want to call them are increasingly more important for all 2.0 people. Often it's not the friend or the funny uncle that will give you advice: It's the guy you've never met but you share a hobby with that will give you insightful advice. These people can be found on major sites (MySpace, Facebook, etc.), on private messageboards, niche sites. They are as trusted (or even more) than friends or family with good but limited knowledge about your specific issue