For people who want to use their TypePad profile (or another service like it) as their identity on the web, it solves the problem for them as they end up with bidirectional links (TP Profile links to Twitter account and Twitter homepage links to TP Profile). For others, as long as there is a bidirectional link between their website/blog/homepage and their TypePad Profile which contains possibly bidirectional links to their accounts on other services then we’re helping to build out their graph with very little effort. If my blog and profile have bidirectional links and my profile links to my Twitter account then it doesn’t matter if my Twitter account links back to my blog or to my profile.

So you’re right, it’s not a solved problem but it is something that will only get solved as more tools – especially the social networks – make it easy.

The row of social network links I’ve chosen to add to my blog may be reminiscent of a dodgy set of Xmas lights, but it’s a simple way to remind people that our social circles probably connect on another network somewhere.

Inevitably, my mom asks “what’s FriendFeed? Do you not have enough friends already?” but to the more initiated, these icons also help illustrate what circles we CHOOSE to belong to (ie. notably no MySpace in my list).

Until it’s dead easy AND normobs see the value of signposting your other web real estate, it’ll only be us geeks, I’m afraid!

I suspect adoption is low right now because a) there’s little benefit right now other than ‘doing the right thing’ and b) laziness or simple forgetfulness.

I’ll add a “c)”: ignorance. This is the first I’ve heard of this property, and I do web development as part of my duties. I suspect that most web devs in the real world are, like myself, “part-timers.” That is, we make web pages as part of some larger programming or media maintenance project. Before writing off this concept, you really should give mass education a chance first.

An initial useful app I’d love to see would be a registration form that pre-filled based on who you were elsewhere. It’s not the greatest app in the world, but it’s a place to start.

Auto-discovery (and likewise easy rejection), as you say, is key. Any action the user has to take to maintain these these links between sites should be kept to an absolute minimum, or they just won’t get created. This is definitely a problem-space I’m looking forward to playing in when I get some time.

I suspect adoption is low right now because a) there’s little benefit right now other than ‘doing the right thing’ and b) laziness or simple forgetfulness.

To solve this, let’s get something built that has real value (a few theoretical examples built with the SG API don’t cut it) and let’s pressure web authoring tools to support rel=”me” properly. WordPress already does, for instance. Bedroom coders and soccer moms won’t ever care about or understand XFN, so our only hope it to make it default behaviour in the tools they use.

I think your /vcard page hints at the way this will go – the triangle of pages is completely logical. I see it that people’s contact pages will link to their presence on other social networks, rather than the homepages themselves. My homepage only performs this link directly at the moment because it’s so sparse.

That said, don’t write off the idea of an actual third party service handling this linking. Check out ClaimID — (see http://claimid.com/factoryjoe for a thorough example) — an OpenID provider whose OpenID page provides rel=me links to everything you tell it. Your homepage, or any page, just need link there.

Now, with a service sitting behind those links, it can offer discover for you and help you manage them. If it checks with the Google Social Graph once a week for new inbound rel-me links to any of your other URLs, if there are any unreciprocated links, it can prompt you to confirm the link (for genuine identity proliferation) or ignore it (for false positives).

I don’t know if ClaimID does that sort of discovery/verification, but they could.

You’re right that the idea of everyone building and maintaining these links by hand is unlikely. But I think that a generation of services managing the connections for us, built on top of XFN, is entirely plausible.