The idea of using social graph data, somehow, in calculating search relevance is a nice idea, but you have to avoid incorrect assumptions like "You will like the things your social connections like."<p>StumbleUpon has used social graph data for a while, to make website recommendations (but they're not a general-purpose search engine):<p><a href="http://www.stumbleupon.com/technology/" rel="nofollow">http://www.stumbleupon.com/technology/</a><p>Ness is seems to be using social graph information, in a clever way, to make restaurant recommendations:<p><a href="http://www.building43.com/videos/2011/08/25/ness-personalized-search-results/" rel="nofollow">http://www.building43.com/videos/2011/08/25/ness-personalize...</a><p>To me, the taste graph (a phrase coined by Hunch, I think) is much more interesting than the social graph, as an extra source of relevancy information. It you know my tastes, and you know the taste graph, then you can say what else I might like (with probabilities).<p>Will Facebook or Google ever use these additional sources of relevancy information? My bets are on Google.