This is an interesting article on an announcement from Twitter co-founder, Ed Williams on how he is trying to drive through how they measure 'success' on Twitter. Currently this is done on the number of followers, however this metric can be massaged giving a false picture of the true 'success'.
Twitter wants to measure success differently and now wants to base the measurement on the number of people who saw you tweet and re-tweeted it.
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Twitter wants to measure success differently