I'm doing this at the moment, about 70% done. You'll be able to invite a character to be a friend but also specify it to be an account wide invite or just a single character, to which the recipient will agree to the request along with the account/character locality of the invite. An account wide invite will therefore show all alts that come online, so in the friends list it will show the friend alt online say Bongo and then the name you actually added if different with it "aka Mongo" underneath of so. If just a specific character friend is added then you'll only see them, and it wont betray any other alts (to which we hope to sort the website top lists to also not betray peoples alts if we can). If you have friends account wide, that grants you access to see all of their alts essentially, for trusted friends.
Most importantly, the friends list will be invite and accept, instead of the current 'stalker list', so a proper mutual friends list. This is to go with the new cross server stuff we did to show friends on different server.
Along with this is coming the mail system very soon, so in terms of system wise content, we're still going forward with all the cross server things as promised, but it is rather complex, but all this is now in place to add Guilds and AH, etc.
One idiom is that the current 'stalker' list will be redundant as we cant assume you have each other as friends, nor can we assume to make those invites for you (cos a % of them are probably added for stalking ), so at the moment, we may well use the mail system to send you a list of your friends names, which you can then choose to invite manually, a bit of a pain but not too bad... at least its a better system