The leaderboard, which was added yesterday, is divided by server. You can adjust the list further by guild name (alphabetically), number of guild members, amount of renown, or guild level.
There are still a few improvements to be made -- some of the guild links are incorrect or don't work, for example. The listing for number of guild members is linked to characters rather than accounts, and many players have requested that an account-based number be made available.
Check out the leaderboard as well as the forums to see what everyone's saying about this new addition.