I blogged about this earlier, and my thoughtsa re that it can be a great system.
Use myself as an example. I have a google Gmail account. I got this account when they were only available on test from google via invitation. I joined Orkut (the original Google social network) when again it was invite only from Google. My friends on Orkut are big hitters with regard Google, I have used Gmail for years, Google have my bank details and have paid me money each month since the dawn of Adsense. They have my WMT data, my Analytics data. They know my Twitter details, and can see who is following me.
I see this as a step of taking their original citation algorithm applying it to the social web, and then transferring that authority to the Serp +1 button.
In Short, not all +1's will be equal.