A problem exists with most social networking services (SNSs) in that they usually do not work together and therefore you are required to re-enter your profile and re-define your social connections when you register for each new site. There have been a lot of complaints about these so-called “walled gardens”. Although many of the most popular SNSs would not exist without the walled garden approach, some flexibility would be useful.
Users may have many identities on different social networks, where each identity is created from scratch. A reusable profile would allow a user to import their existing identity and connections (from their own homepage or from another site they are registered on). If data about a person is aggregated from various social networks and linked together using a common representation format, a single global identity can be formed with different views and associated reputations / histories.
Semantic Web vocabularies such as FOAF and microformats like hCard and XFN can serve as useful platforms for linking or reusing the diverse information about a person from heterogeneous social networking sites and for performing operations on such reusable / linked data. This can then be used to provide an enhanced view of an individual’s activity in a distributed social network (e.g., “show me all the content that Alice has acted on in the past three months”).
“Social network portability” is a term that has been used to describe the ability to reuse one’s profile across various social networking sites and applications. The founder of the LiveJournal blogging community, Brad Fitzpatrick, recently wrote an article (with comments here) from a developer’s point of view about forming a “decentralised social graph”, which discusses some ideas for social network portability and aggregating one’s friends across sites. Dan Brickley, the co-creator of FOAF, has also written an elegant discussion (entitled “the world is now closed“) about how SNSs should not define your relationships in absolute terms and that even an aggregate social graph cannot be so clearly defined.
In parallel with this, a social network portability mailing list was established which has seen over 400 posts on this topic since August 17th. Activity on the list peaked soon after (see graph below), but many interesting topics have been discussed including centralisation versus decentralisation, FOAF, XFN, hCard, OpenID, Bloom filters, ownership of your published content, categorising friends and personas, the OpenFriendFormat, SNAP, aggregation and privacy, and XMPP. You can read more on the list or join it to post your own thoughts.