"the pendulum is going to swing from public data to private." writesTim O’Reilly.
A segmentation is already occurring within the social networking world around contacts and information.
The first level is where ClearContext plays, within people’s Outlook email. From within Outlook, there’s full access to both email content and its relationship with contacts. This allows for lots of very powerful information to be gathered, but it is all private and controlled by the user, a totally closed system from a visibility standpoint.
The next level is a site like LinkedIn, where people get a certain degree of visibility into your contacts. The system is semi-private, so people are willing to share detailed business information on there as well as share valued contact information to a degree. However, the flip side of that is that many people also restrict access to that information to a trusted network.
Facebook is the next level of openness. Here "friends" takes on a much less important meaning for many, often meaning "someone I met once or saw somewhere on the Internet." Profiles have much less "proprietary" information that people want to protect, thus they often are open to a much wider group of contacts to share with. But people still put a lot of personal information on there, so a certain degree of access restriction also occurs.
Even "lighter" forms of communication take place on Twitter. The same can be said for fun interest-oriented social networking sites like Flixster or even Yelp. At these sites, there’s nothing proprietary or private about what’s being written, so people can be completely free with their contact and information sharing across these sites.
Somewhere in there is the sweet spot of valuable, proprietary information and a broad network of contacts to aggregate and share across. Developing ways to bring those things together is where a goldmine of value exists.