I've finally ventured over to the Test Realms and copied a character across, but I haven't done much with her due to other things going on. The intention is there, so maybe in the future I can experience content before it's released and have time to write about it a little before it comes out for everyone to use.
One of the many new features coming forth in Patch 2.3 (currently live on the Player Test Realms) is the introduction of a Guild Bank that is controlled by the Guild Master of any given guild.
This one change is bound to be interesting over time - to see what kinds of guilds begin to use it and which stay with their old toon-based banking structures, for example. (kind of like in-game voice chat vs Vent - Vent is still winning for now)
Guild Banks Aren't New
Despite the fact that there were no Blizzard-supported Guild Banking structures before Patch 2.3, most guilds, and even many players, had a "bank account" set up. That is, they have created a character in the game whose job is to live in a city and handle item storage and auctioning responsibilities. Usually bank toons have large volumes of bank and bag space to accomodate for the volume of items they store.
Depending on the function and size of your guild, and the level of its members, a wide variety of things could be stored in this "Guild Bank" - equipment, potions, professions materials, consumables for guild-based dungeon runs, flasks for special raid attempts, etc.
Pre-Patch 2.3 Guild Bank Problems
The main problem of this type of underground, player-created "banking" system (created since there wasn't a Guild Bank facility within the game until Patch 2.3) was a lack of transparency: Only the owner of the account who had the bank toon character listed could see the full Guild Bank inventory.
Lack of transparency in a Guild Bank account can quickly become a problem in a growing guild because even if there isn't abuse of the privilege going on by the owner of the Guild Bank (ie: selling off guildie-donated items and buying goods for self from the proceeds), an imbalance of donations versus withdrawls can begin within the membership, as each see themselves worthy of different levels of assistance from the guild itself.
Addressing the Transparency Issue Pre-Patch 2.3
In order to address the Transparency issue, there have been countless addons developed by the player community to help guilds manage their guild banks and provide accurate, browsable lists of bank contents to the guild populace.
Intro To Guild Bank 1.0, Patch 2.3
I haven't been able to review it yet, but I have found this thread on the Official Forums that includes screenshots.
What Will The Effect Of Patch 2.3 "Guild Bank 1.0%26#8243; Be?
Will guilds immediately adopt this? Will the viewable logs and contents deal with the transparency issues of the past? What new problems will crop up?
Stay tuned for more posts on this exciting topic ;)