From The Original Article: "One of the greatest joys of site migration is discovering that your social share counts don’t follow 301 redirects. But those Facebook Likes, Tweets and Google +1s that we’ve worked so hard to capture don’t have to evaporate with a click of a mouse.
As social metrics mature within search engines, there is worry that site migrations will cause these metrics to be discarded. It is of no leap of logic to assume that search engines will pass the value of the social share through a 301 redirect.
Therefore it should be enough to maintain the social shares on the original URL and display them at the new one.
Essentially for each of these you will want to identify the URL of the original page and set an attribute on social share button to show the shares of the old URL".