The online social landscape today sort of feels to me like search did in 1999. It’s a mess, but we don’t complain much about it because we don’t know there’s a better way.
Everything is decentralized, and no one is working to centralize stuff. I’ve got photos on Flickr, Posterous and Facebook (and even a few on MySpace), reviews on Yelp (but movie reviews on Flixster), location on Foursquare, Loopt and Gowalla, status updates on Facebook and Twitter, and videos on YouTube. Etc. I’ve got dozens of social graphs on dozens of sites, and trying to remember which friends puts his or her pictures on which site is a huge challenge.
What enabled Google to solve the search problem was a common standard for expressing pages and the links between them, so that they could index the webpages and derive a metric for which ones were more important. They didn't do this by replacing the web with a structured database that they curated, they worked with the standards in use to make sense of it.
To solve the social conundrum we need the equivalent - agreed standards in widespread use so that we can generalize across sites. Fortunately, we have these. We have OpenID and OAuth for delegated login; we have XFN, other microformats and Portable Contacts for public and private people connections; we have Feeds and Activity Streams for translating social actions between sites.
This enabling social infrastructure means that we'll be able to have a new generation of sites that enhance our web experience through social filtering without our connections being centralised in a single company's database.
Once we get used to the experience of being able to delegate login, personal connections and activity updates, we'll look askance at developers who insist we create yet another profile and invite all our friends by email to experience their site; it'll be like a website without links.