Start off by taking a look at the 'Coke' group on facebook. They have more that 3 million facebook users who have joined the group. Each of those users invites

Start off by taking a look at the 'Coke' group on facebook. They have more that 3 million facebook users who have joined the group. Each of those users invites other users to join the group. Now Coke can 'push' a message to everyone of those 3 million users without any cost at all. It's advertisement, but there is no budget at all! But it's more than that, Coke can actually look at what its biggest fans want. They have a 3 million strong userbase against which they can run surveys, see what the feeling about marketing campaigns is, etc. Also, everybody who searches for a particular persons name on google will likely see his facebook page appearing. The public search listing for the person includes the message 'Coke'. This is akin to a personal recommendation from one person to another, that coke is good. This is a dream scenario for a brand. Twitter is useful when the brand is a personality. People want to interact with brands who are personalities, and twitter offers a direct way to do so, and create personal nuance in the brand.