Blizzard has posted new details on new social features coming to Diablo III on the PC. These new social features will be available to owners of the upcoming Reaper of Souls expansion. It's unclear whether owners of the vanilla game will have access to these features.
Clans will allow up to 120 players to join, a number chosen by Blizzard because clans are intended, they say, to be smaller and exclusive. Players can only join one clan at a time.
In addition to clans, players will be able to partake in communities, which have unlimited members and do not require an invite. Players can join as many communities as they like, and for any reason including playing the same class, frequenting the same fan sites, or living in the same geographical area.
These features are undergoing testing on the public test realm and are expected to be available once Reaper of Souls is released.
Further details can be found at Battle.net.