You’re right, PostRank is a measure of social engagement with an article. A story that gets more traction – be that via a large discussion, or a large number of bookmarks – will have a higher score. Having said that, a spam war in the comments section may not contribute as much to the PostRank score as you may think. ;-)

As well, we intentionally kept PostRank as a score with respect to the feed, and not a global metric. This allows our users to personalize their filtering experience. For example, I may want to subscribe to a small tech. blogger, who in comparison, might be obliterated by slashdot’s stats – our system allows you to do that. (‘I want the best of this blogger, irrespective of how big or small the site is’).

Having said all that, I think you’ll be pleased with some of the features we have in the pipeline – stay tuned! ;-)