Yes and no.

Yes, in that part of what you do is to tell Google "I trust these people" and give them higher ranking than random "search engine optimized" pages.

No, in that someone who follow the hacker news circle and search for "android" will likely prefer results about programming and marketing android applications, which are not the optimal results for the general public.

So the social graph does to things: it states trust (improves general quality of results), and it states interests (improves specific targeting of results).

The later obviously is more likely to work for interest based circles like "hacker news" than for your Family or even Friends circles.