Here is a short and interesting video about the growing importance of citations to SEO. It is cool to see how Google's relevance algorithms are getting more sophisticated at understanding the meaning in content and identifying authority. Of course, the pessimist in me sees SEO bottom feeders interpreting this trend as justification for anti-social behavior like comment spam.
In the arms race between Google and the people who try to manipulate it, always side with Google. If you create great content and build an audience of influencers, you are Google's ally. Take short cuts and play tricks and you are one algorithm change away from total obscurity.