How does it work?
Anyone know?
Guild rep is built from a % of xp from quests, instancing, and pvp (I believe) when running with guild members. The % changes based on how many in the group are from your guild. The higher the guild rep overall, the more your guild overall levels. The higher the guild rep you have wiht the guild, the more your guild priveleges increase. This is from blue poster Mumper:
Guild experience can be earned in any of four ways:
1. Completing quests / daily quests that reward experience
2. Killing any dungeon / raid boss with a guild group/raid
3. Winning a rated battleground with a guild group/raid
4. Earning a guild achievement (these are nice, fat chunks of experience so they feel great when you get em)
A guild group/raid is 4/5, 8/10, 12/15 or 20/25 members of the group/raid being guild members.
From what I understand, it is not yet active, but the bones are there to make it live. There are still a number of guild management issues taking place on Beta, and they had dissolved guilds recently to start things anew.