This is a good article that share information and research about the power of retweeting and who's the most influential.
Twitter Users Who Rack Up the Retweets Top Most Influential List
Got a lot of Twitter followers? So what? Unless they're listening to what you're saying and actually passing it on, you're likely not all that influential, according to a new study by HP Labs.
According to the study, “The correlation between popularity and influence is weaker than it might be expected. This is a reflection of the fact that for information to propagate in a network, individuals need to forward it to the other members, thus having to actively engage rather than passively read it and cease to act on it.”
Dr. Bernardo A. Huberman, the director of Hewlett-Packard Labs' Social Computing Lab, and his team analyzed 22 million tweets over 300 hours in September 2009 in order to concoct what he calls the IP Algorithm, which highlights influential Twitter users by assigning them both a score for influence and passivity.
Passivity is the tendency of many followers to passively peruse tweets without sharing them (i.e. retweeting them) with their network. According to the study, the average Twitter user retweets only one in 318 URLs.
Those Twitter users who are truly influential are able to break through this blase shell and impel their followers to share their tweets with the rest of the Twit-o-sphere. Check out the most influential Twitterers below (Mashable got a mention), as well as the most popular, yet not-so-influential users.