In reviewing Danah Boyd’s elaborated definition of social network sites, she says:

We define social network sites as web-based services that allow individuals to (1) construct a public or semi-public profile within a bounded system, (2) articulate a list of other users with whom they share a connection, and (3) view and traverse their list of connections and those made by others within the system. The nature and nomenclature of these connections may vary from site to site.

From her analysis of SNS, I am of the opinion that most people don’t use SNS as a cross cultural meeting place. People tend to use SNS to communicate with people they already know. It seems that various groups seem to adopt particular SNS for their communication.  For example:

Many SNSs target people from specific geographical regions or linguistic groups, although this does not always determine the site’s constituency. Orkut, for example, was launched in the United States with an English-only interface, but Portuguese-speaking Brazilians quickly became the dominant user group (Kopytoff, 2004). Some sites are designed with specific ethnic, religious, sexual orientation, political, or other identity-driven categories in mind. There are even SNSs for dogs (Dogster) and cats (Catster), although their owners must manage their profiles.

So the cultural message that Danah Boyd is seeming to present is that there are cultural groups that exist through the pipeline of SNS, but they tend to stay in their own already formed groups instead of using SNS as a primarily social network group building endeavor.  So SNS groups serve mostly as a means of social communication, sort of like email on a grander scale or IM.