As I recently started leveling up another character it came to my attention that some people were still unaware that you can transfer heirloom items to characters of the opposite faction. For example, if you already have a bunch of heirloom items on some alliance toons you can now send your heirloom items to a horde character on that same server.
Don't get too excited about the prospect of possibly transferring gold or bags to this character though because it still cannot be done, but I'd say that the ability to mail the heirlooms is something good.
