The lastest Warhammer Grab Bag is up for your reading pleasure
Check it out has some more good guild info.
A tiny piece:
Originally Posted by Mythic Entertainment
Q. Your answer in the previous Grab Bag regarding guild leveling was confusing. Can you please clarify exactly how guild experience is calculated, and what constitutes an ‘active’ character in a guild?
A. While it’s against our policy to share exact formulas (in order to keep guilds from gaming the system), we do want to be sure and clarify these mechanics to the best of our ability for those guilds who are concerned about how guild leveling actually works. The total number of members in a guild does not impact Guild XP gain directly. It's based on characters who have recently contributed experience. The system takes into account the characters’ level, and is balanced in a way to allow guilds of all sizes to level up at comparable (but not necessarily equal) rates.
It is a sound system involving a lot of math, which is designed with the idea that players have alts and that there are as many large and small casual guilds as there are large and small hardcore ones. There is no need to boot inactive characters from your guild’s roster. If a character has not logged in, that character is not affecting the contribution rating at all. Our ultimate goal when designing this system was to ensure that all types of guilds are able to level up on an equal playing field whether they’re large or small, casual or hardcore.
In the end, it’s important to remember that guilds are an enriching social environment that are a great way to enhance your gameplay. We encourage players select a guild that values you for who you are, and not solely for your experience contribution.
Q. Is the only way to level a guild up through actually leveling characters up or what?
A. Not necessarily. Any activity which normally yields experience to the player will contribute experience to the guild. Even level 40's continue to contribute guild experience as long as they are participating in activities that lend them experience.