Personally, I think this can work well for my searchers. But for most of those who do not have Google Profiles set up, it likely won't add much. Google currently promises to only look at information you give to them via your Google Profile or via Gmail. For Google to know who your Twitter connections are, you need to share that information on your Google Profile. Then Google will crawl your social profiles and make a map of all your friends, and associate what they read in Google Reader, share, click on and produce with you, when you search.
Here are two videos explaining it all:
Of course, there are some worried that Google will go beyond their boundaries and figure out your social profile without you specifically sharing it. Google said they won't, but many don't trust Google.