Nova Spivack pulls apart the business logic - starting with desktop apps and then moving on to web-hosted services like Orkut and Flickr - and analyses the usefulness of social networking after we get done with the pleasantries, and the fun of meeting people we actually like.

Social networking is a "nice to have" not a "must have" technology. Here's why: Social networking tools offer little to no value-add for interactions with people whom you already have relationships with and with whom it is far more efficient to simply send direct e-mail, use the phone, or IM. If you already know someone why bother locating them in a social networking tool and interacting with them via several intermediaries? So where is social networking useful: Social networking tools only add value for locating, establishing relationships with, and interacting with, people whom you do not already have relationships. But how often, and in what contexts, do we need to locate and interact with people whom we don't already know? The answer is that social networking (technology) is really only useful for "marketplace" activities such as business development, sales and marketing, dating and classified advertising and communities.