In a seemingly 'by invitation only' experiment, Google is toying with adding social interaction to their current results scheme. Reactions on blog posts seem to be mixed. Personally, I couldn't be more excited by it and hope they open up the experiment soon as I'd really like to join the fun.
Comparisons have been drawn to offerings such as Digg or Mahalo, but this seems to sit somewhere in the middle. While there are legitimate concerns around the impact to SEO and the risk of people 'burying' legitimate information in an organized fashion (think a competitors site), my experience continues to suggest that social networks are self-policing and these end of the world scenarios generally don't come to fruition.
Where I think this gets really interesting is if / when results can associate themselves with my social circle of friends. In other words, it's great that seven million people have favorably rated a result - but how about when I can narrow that down to the rating by my online peers whom I have a relationship and trust based on common interests.
I applaud Google for the move and think it highlights their focus on the evolution of their core offering.