A few years ago, I created my FOAF profile with FOAF-O-Matic. But actually, I almost never updated it and its foaf:knows list.

So, now, I’ll let external websites manage those informations.
I have exports in RDF of my flickr, twitter and facebook accounts, as well as this weblog (in progress), and in most of them, I define those relationships to the people I know. Since all those files define a URI for myself, I can use my main (I mean hosted by my own) FOAF file as a reference profile that will link myself to my other URIs using owl:sameAs, and also add rdfs:seeAlso links to the related files (as described here), eg:

<owl:sameAs
  rdf:resource="http://apassant.net/home/2007/12/flickrdf/people/33669349@N00"
  rdfs:seeAlso="http://apassant.net/home/2007/12/flickrdf/data/people/33669349@N00"/>

<owl:sameAs
  rdf:resource="http://twitter.com/terraces"
  rdfs:seeAlso="http://tools.opiumfield.com/twitter/terraces/rdf"/>

And I’ll get a decentralized foaf:knows network, as shown on this graph:Then, I can grab all these profiles in a local RDF store, or even better, use a dedicated Semantic Web “social graph manager” as Knowee or Beatnik to get all my contacts locally, get their e-mail, query profiles, or as David said, integrates in other desktop apps and sync with my iphone (ok, I don’t have one yet ) …

And if services as linked-in or bibliography repositories export FOAF URIs for anyone, as the FOAF/DBLP service already offers, I could even link to people I worked with. In case all those services exports data with only foaf:knows and I want to be more precice, I can refine relationships in my profile using the RELATIONSHIP vocabulary, or maybe even include rules in my profile that could then be taken into consideration by agents that will query it ? Something like:

( GRAPH <http://linkedin/foafexport/mygraph> { #me foaf:knows ?x } )
=>
( #me rel:collaboratesWith ?x )

that will be in my profile itself.

Finally, since I can create a link to this FOAF profile from my OpenID, I can reuse this graph in many applications. And when login to a new service, ask him “is there anyone here that I know from flickr ?”.

More than social network, I can also link from the same profile (or, actually, from the profiles that have been linked to the reference one) to various things I wrote or done on the Web, as data from last-fm, revyu or flickr, thanks to SIOC, as explained here.

So: One reference profile. Lots of distributed information. One Giant Global Graph.

NB: Also check some of Dan Brickley’s experiments about related topics.

NB2: I did not take trust issues in consideration in that post, i.e. how can we be sure that the owl:sameAs relationship is linked to an URI which is really *me*. I think one solution would be to authenticate on those websites using OpenID so that it can find my FOAF file, then my URI, and add an owl:sameAs link in the other direction. Both files should also be signed, and I think that will be ok (?).