This is the first step in a MASSIVE change in the way search works.
Why is this a massive change? With true torrents of content emerging from Twitter and Facebook, it will be impossible for the search engines to use their traditional metrics to determine what an authoritative search result is. The traditional authority based algorithm becomes significantly less relevant.
Today, you can see what is happening at Twitter through Bing at http://www.bing.com/twitter. This isn't as much true integration with search results, as it is a separate search experience. But as search engines move to some kind of universal search experience, it is inevitable that these real-time search updates will compete for prominence with the "traditional" search results. So why does this matter?
Natural search engine results are ordered through a complex algorithm, but one of the primary indicators of authority (and, therefore, more likely to appear at the top of the listings) is how many quality links point to a page. Typically, the higher the quality link to the page, the higher the page shows up in search results. But in the new world of torrents from Twitter and Facebook, there is no time for any tweet or Facebook posting to grow this link-based authority. So, other than timeliness, how will the torrent be ranked in authority?
There are dozens of ways to think about this. Perhaps it is the number of Facebook friends or Twitter followers that help you gain authority (though that seems ripe for abuse by spammers)? Or maybe it is how long you've been tweeting or Facebooking? But that seems a silly way to determine authority in a real-time world.
It will all come down to REPUTATION.
Reputation is the new page rank.
Although this is speculation on my part, I think that based on who follows you, and the relative importance of you in the context of your follower's entire social network, your authority will come from how reputable you are to your social network. (If every follower clicks on a link that you publish or if you have a bigger share of voice inside your social network than others, you would score highly in a reputation index.) And the higher your reputation index, the more relevant, the more authoritative and the more visible your social stream will be in the search results.
The next step from reputation is localized reputation and personalized search results. But we will save that story for another day.