World of Raids has released a torrent of official Cataclysm information this week. Here's what they discovered about changes to the upcoming Guild System:

Guild Leveling

• There are 25 levels in total.
• Guild talents are not going to be implemented.
• Instead, guilds will be automatically rewarded with perks.
• Each time a guild levels up they will receive a perk.
• Guilds gain experience through a member participating in dungeon or raid boss kills, winning rated battlegrounds, completing quests or unlocking guild achievements.

Guild Rewards

• Guild currency has been scrapped.
• Guild rewards will be unlocked by completing guild achievements.
• Rewards will be purchased with gold, and anyone in the guild can purchase the reward once it's unlocked.
• Examples: mounts, tabards, heirlooms.
• Guild mounts will have a flag attached to them that displays the guild's emblem.

Guild Reputation

• This is a newly announced feature; players will gain reputation with their guild similar to how other reputations work in the game.
• As you contribute to the guild by completing quests, killing bosses, winning rated BGs or completing guild achievements, you will gain reputation.
• The best guild rewards will require having exalted reputation with your guild.
• Guild reputation is on a per-character basis, so you'll have to gain rep for each character you have in the guild before you can buy rewards with it.
• Reputation is not wiped immediately upon leaving or being removed from the guild; this is to prevent losing all your progress in the guild due to someone jokingly kicking you.

Guild Achievements

• These will be integral to the reward and level systems. Completing one can unlock rewards as well as give the guild experience.
• Guild achievements are earned and owned by the guild, so once it has it, it never goes away — even if all members who participated leave the guild.
• Even classic raids will help level your guild. A new version of the classic raid meta will become available that guilds can complete.
• When viewing a guild achievement it will display the members who participated in earning that achievement.
• To earn a guild achievement you must have 7 of 10 or 20 of 25 players in the raid be members of your guild.
• There will be realm first achievements for guilds, as well as individual players.
• Current raid achievements will NOT be retroactive. New guild versions of the achievements will be introduced. This is to start Cataclysm with a "clean slate," according to Cory Stockton.

Guild Window

• The guild UI has received an overhaul and contains:
  • The guild xp bar and its current level.
  • An RSS-like feed of the latest news for the guild; boss kills, level milestones, etc.
  • Some news like major raid boss kills or level 85 will be "sticky" (this is determined by Blizzard) and will persist at the top of the feed for a while.
  • An upcoming events section that is a snapshot of your guild's calendar.
  • The most recent perk the guild has earned, and the one for reaching the next level.
  • The guild reputation bar (this is specific to your character).

The guild roster page has also been overhauled and now contains a professions display for each member.

You will be able to click on profession icons and view the recipes a guild member has, even while they're offline.