Might this be a backdoor for Google to understand the relationship between sharing and quality? Or maybe a way to subtly promote +1 to webmasters? Yes, maybe, and possibly even more.
Google’s ranking algorithm is heavily dependent on backlinks, but what happens when people’s content interaction behavior changes over time? How many people used to maintain their own “homepage” or blog (via Blogger or MySpace, for instance) and were heavy linkers, but instead live on Facebook now and just share that way? I suspect the pool of authentic backlinks is shrinking, while Facebook Like and Tweet counts are growing.
My speculation is that Google might be able to grab Like and Tweet numbers shown on a page using those buttons, but might not yet be ready to incorporate them as a signal in its search algorithm since Google doesn’t have too much insight into what’s behind them. I’m sure Google would like to know if those numbers are evenly distributed among a large number of readers, or among a relatively concentrated, small group of readers (like the author and his/her friends), or the workings of a spammer. It probably knows that 500 Likes or Retweets is better than 5, but it can’t tell by how much. By getting access to richer data via the API, it can probably add some color to these raw numbers. Note, though, that Google consistently says that it does not use Analytics data in its search algorithm, so that’s a loop that might not yet be closed.
Another way Google can recognize the true value of the social sharings of a piece of content is by the +1 button. Through the rel=author/rel=me tags, Google should have a good idea if someone +1ing a piece of content is the author of the article, or friends of the author who do reciprocal +1ing. If Google sees a fair number of +1s that are most authentically sourced, then it might see the social sharing of the page as legitimate; if most the +1s are from the author and his/her friends, then it might not have the same impact. This is the reason that, when we do roll out the +1 button to Hubs, we caution Hubbers to be judicious in their use of it; overzealous +1ing of Hubs and your other content might invalidate them and any other +1s you’ve made.
Google predictably shares very little information publicly about matters related to its search algorithm, but I suspect the +1 buttons and Analytics/Webmaster Tools support for Facebook and Twitter data are just the beginning of what we can expect as Google digests the impact of social sharing on search.