Social networks a peer to peer problem?
There have been several (many) posts apophenia: why Orkut makes people insecure bashing Orkut for many reasons. The majority of the posts are valid but I do not see that the problem is unique to Orkut.
Trying to create a general set of semantic information to bring together large numbers of people is inherently an almost unsolvable problem the way Orkut and most of the other networks addresses it. The meaning I assign to any of the fields I select in Orkut is probably different from how others assign meaning. This is a classic problem with using shared semantics - i.e. how do we arrive at the shared semantics. Having a centralized authority specify the semantics (and in the case of Orkut a limited set) is the wrong approach (IMHO). What needs to happen is that the infrastructure should enable peer groups to form around common semantics (or Topic Maps).
There needs to be shared infrastucture to enable social networks but the actual semantics need to be created in a peer to peer interaction between individuals. Is something like Easy News Topics a good start? perhaps, but we need to figure out how to make this easy to use, while delivering benefits to users.