The PlayOn Group at PARC has been gathering longitudinal census data from several WoW servers. I gave a list of links to some interesting data points from the last issue of the Daedalus Project and I wanted to link to some of the more recent data that is available at PlayOn.
1) Check out this post on visualizing the social networks in WoW guilds.
2) When players leave a guild, they mostly do not seem to have a guild they are intending to switch to instead.
3) Of all guilds seen in a one-week period in June, 21% were not seen in a one-week period in July.
4) Of all characters seen in a one-week period in June, 46% were not seen in a one-week period in July.