Google is currently rolling out it's latest alograthms and more than ever social share is now massively important. Please Rich I know I've been banging on about this for over a year now but please I think more than ever the social share discount is a really essential update.
Whilst I'm at it, please can we have a Pintrest add button as again this is building in relevance and is all about social share (which is what the new alograthms are based on). If it can be added next to the +1, FB and Twitter buttons that would be better still - http://pinterest.com/about/goodies/
If anyone wants to read about the google updates this is quite a nice article - http://www.eddale.co/internetmarketing/winter-is-coming