At a basic level, as Ted says, the ability to change some basic profile data in one place is useful. There is nothing worse than having to update your email address, msn or whatever at all the different social networking sites just because some of your friends happen to prefer using one and not the other, or you have multiple personas.

Of course maybe version 2 of such a system would allow you to intelligently manage your identities across different sites so you can have a public and private persona, or even multiple of each!

To pull something like this off though, a social network API standard is needed.

It’s a shameless self plug, but even if it were someone else’s project I’d mention it. You just described a lot of the ideas behind FindMeOn.com : every online account listed becomes its own URL + widget + API feed that other services can point to for a data-sync — and you can explicitly hide / link different online accounts from one another. The example we’ve been using for the past few months is that you dont want your myspace stalkers to see your family photos, and you don’t want your family to see whats going on in myspace.

Working in tandem with the commercial offering is an open standard node structure at findmeon.org — which uses public-key cryptography to link + shield online accounts from one another.

The one place I do see a convenience would be a single profile source where you can share the basics (optionally to include: name, home town, blog URL, photo URL, dating status, AIM, YIM, flickr, etc.)

Then when you join a new network that isn’t too important to you, you can submit your shared profile URL where the new site can suck in your info each on a regular basis. If you get married, or want to show off your new nose ring, that status or photo is reflected immediately instead of having to change them on each site.

But even this I would see as only a option for social sites you’re not that into, where you aren’t using a photo or name that doesn’t more precisely reflect your association to that topic.

People will have, and use, various identities: the social me, the business me, etc. It would be wrong to smash all those together and that’s not what I’m suggesting.

I am suggesting that where the attributes of the social me overlap on Flickr and YouTube and elsewhere, I should have the /option/ to consolidate.

As you suggest – I don’t think exposing all your identities across all your social networks to the public via aggregation is not necessarily a desirable outcome.