What I found more interesting is the "usage distribution" of Twitter:
Although men and women follow a similar number of Twitter users, men have 15% more followers than women. Men also have more reciprocated relationships, in which two users follow each other. This "follower split" suggests that women are driven less by followers than men, or have more stringent thresholds for reciprocating relationships. This is intriguing, especially given that females hold a slight majority on Twitter: we found that men comprise 45% of Twitter users, while women represent 55%. To get this figure, we cross-referenced users' "real names" against a database of 40,000 strongly gendered names.
Even more interesting is who follows whom. We found that an average man is almost twice more likely to follow another man than a woman. Similarly, an average woman is 25% more likely to follow a man than a woman. Finally, an average man is 40% more likely to be followed by another man than by a woman. These results cannot be explained by different tweeting activity - both men and women tweet at the same rate.
Twitter's usage patterns are also very different from a typical on-line social network. A typical Twitter user contributes very rarely. Among Twitter users, the median number of lifetime tweets per user is one. This translates into over half of Twitter users tweeting less than once every 74 days. At the same time there is a small contingent of users who are very active. Specifically, the top 10% of prolific Twitter users accounted for over 90% of tweets. On a typical online social network, the top 10% of users account for 30% of all production.... This implies that Twitter's resembles more of a one-way, one-to-many publishing service more than a two-way, peer-to-peer communication network.