Just noticed that the Web Ecology Project has published “The Influentials: New Approaches for Analyzing Influence on Twitter“. The blog post includes a link to their full report.
Their approach strikes me as a generalization of measuring retweets, but perhaps I’m giving it too cursory a read. I did compare their results to TunkRank: we at least agree that mashable is more influential than CNN–though even as simple a measure as follower count would confirm that judgment.
Anyway, I am delighted to see serious researchers looking at this problem. I’m still hoping to investigate hypotheses regarding TunkRank and friend:follower ratios.