In Malcom Gladwell’s book The Tipping Point, he describes a certain class of people as “connectors”.  They’re people who know everyone, and thus are capable of spreading information and ideas quickly.  Social networks hint at leveraging these personal connections in digital form, but so far have failed to do much with it.

LinkedIn is the only application I’ve seen that really explores this idea from a social networking perspective.  Your network, the number of people you have access to, grows exponentially with each relationship you add.  And if you connect with one of those "connectors" your network will grow even faster (because you become connected to the people they know).

While it makes for an interesting interface and a fun way to explore social connections, LinkedIn--and all the other social networks I've seen--really don't do much with this connection data.  You can ask your network a question or see who’s hiring in your network, but it’s mostly just for ego gratification.

OpenID and FOAF change all that.  All of a sudden people become ACTUAL connectors, connecting together pools of meaningful, rich data that applications can use. 

Two applications which speak OpenID and FOAF all of a sudden have a common data element, a JOIN in SQL-speak.  It's possible because OpenID turns a person into a URI, which naturally lends itself to be used in FOAF.  FOAF is just a list of people, after all.

This is really cool stuff.  It’s automatic data integration across the Internet, using people as connectors. 

This is reason why Kingsley and a bunch of other people like to call the "Semantic Web" the "Linked Data Web".  Potayto-potato, it's all the same to me.  It’s cool, though.  It lets an application traverse the social graph to do its thing instead of being confined to its own network.  It allows an application on one network to access Person C’s data, on another network, by going from Person A to Person B to Person C, and then to their data.

I thought (still think) this was really cool when I finally understood it, and I don’t think many people have an appreciation for the opportunities this opens up.  Although, with the recent traction OpenID has been getting I think it's only a matter of time.

P.S.  This data integration using humans as connectors won't work via proprietary API's or microformats, by the way, because the enabling technology for this is SPARQL, which requires RDF to work its mojo.  Exposing proprietary API's means that you have to custom duct-tape together the data using middleware.