Social Network Marketing uses already established social networks to infiltrate the marketing message. Another way is to establish a social network around a brand or product.
Using social networks as promotional tools is a pretty smart idea. The whole network is already set up. As friends are connected with friends of friends of friends, viral marketing is just a click away. People freely give away all kinds of information, starting with name, age and email-address, to hobbies, interests and almost everything else which is necessary to dig into the right target group. The challenge is not to interfere too clumsily, because that might scare away the users. Not many solutions are out so far, but marketers are starting to get the idea!