Great question, take a look at our indepth description on postrank.com.
PostRank scoring is based on analysis of the "5 Cs" of engagement: creating, critiquing, chatting, collecting, and clicking. By collecting interaction metrics from around the internet our system calculates the overall engagement score of each story and a PostRank value is determined.
The plugin integrates PostRank social media analytics features directly into your admin interface. The Manage Posts page will display each post's current PostRank score, and hovering over it will reveal your current engagement metrics from around the web: delicious/magnolia bookmarks, twitter/jaiku messages, diggs, and many others. See the Screenshots for examples.




