iChat: Add new account in Preferences, select type Jabber, enter username "<username>@chat.facebook.com" (where username is selected in Facebook settings, and you need to logout from Facebook after that change). For password use Facebook password.
New account, select XMPP as protocol. Username is your username (which is your slug if you have a custom url. So I'm facebook.com/daniel.jackoway, my username is daniel.jackoway). Domain is chat.facebook.com. Password is your password. Only gotcha is that you then have to go to the "Advanced" tab and uncheck "Require SSL/TLS".
account add jabber FACEBOOK_USERNAME@chat.facebook.com FACEBOOK_PASS
account list
account add 2 (or whatever number the above list shows is Facebook)
# you'll need to do a /whois on your friends and rename them:
rename u393222111 John
rename u134322433 Bob
So, from what I understand, this is a way for clients like Adium to connect to Facebook chat, but it isn't a way for things like Google Talk to interact with Facebook Chat. That's disappointing. It would have been nice if they announced that they're trying to get interoperability with other networks going.
Most people who use FB chat are probably going through the FB site. Dealing with authorization/privacy/spam/abuse for federated users would be a pretty difficult UI/support challenge since it's not integrated with FB's existing friend/profile privacy concepts.
It's not that difficult. GMail does it. So, xyz@gmail.com requests to add abc@chat.facebook.com to its contact list. In the Facebook web interface, it comes up in the list of groups that you are requested to join, friends to confirm, etc. Privacy settings for vCard stuff (like image) can be the same as they are for Facebook - and Facbeook can use the Jabber ID of the other party (xyz@gmail.com) to see what their Facbeook account is for that or just give the public information (most people have a public profile picture).
SPAM and abuse isn't that hard. Remove the person from your contacts. Done. They can't contact you any more. Really, it's the same as if one of your Facbeook friends was creating SPAM or abuse.
Basically, it's just "friending" people by Jabber ID rather than by Facebook user id in a "chat contact" status.
There are technical challenges to federation and it did take Google a while to implement it. However, the UI, SPAM, and authorization parts don't seem that challenging. And it would be nice if Facebook opened up a bit. And Facebook might be working on this, but I don't think it's a UI issue. In the long run, it will come down to whether Facebook wants to be closed or open and that's a policy decision.
I thought it would be a more obvious question, but how do you think this will affect the other big messenger clients/protocols? MSN/YIM/AIM/GTalk ?
I already noticed a trend in which a large portion of my friends will use facebook chat now and not even bother to login to MSN Messenger (which is the most popular client in my geographical area).
The massive benefit for me is that all my friends are already on Facebook. It's effectively got automatic roster management, which is a killer feature since I don't normally get round to adding people to MSN (which is also the most popular client in my geographical area).
I reckon that because Facebook has such a large number of users already, this has the potential to kill the other IM networks. Maybe it's not so good for properly federated XMPP, though, since this also presumably means that Facebook have no real incentive to implement it.
However, facebook's xmpp implementation is even more restricted than google's so far. It's not even federated as of yet (not that facebook sees a need for their users to communicate outside of their network). Not federated means things like [twitterspy](http://dustin.github.com/twitterspy/) won't work.
They also don't pass many stanza types through. For example, I've seen complaints of people trying to send jingle IQs through in order to establish direct connections between two users. That's not there (yet?).
However, it does mean that you don't have to get a new chat client. I added another account to adium as xmpp and all's well. Just hoping people don't actually start talking to me over it.
It's annoying that once software products become extremely popular, the developers/companies often start adding features in an attempt to be everything for everyone. This in turn makes the software unusable, because the developers are too overloaded to properly maintain their once core business. Eventually it gets replaced by a new product, and the cycle repeats itself.
I'm not sure that this applies here, though. Facebook is ideally suited to hosting "proper" instant messaging, because it has the added bonus of automatically managing the roster list. I don't need to add anyone, my friends are already all on there. That's a massive bonus over any other instant messenger for many, many people.
The Pidgin instructions are incorrect. The "Local Alias" field should be set to your name, not "Facebook Chat", as this field controls what name is printed next to your messages in your local chat window.
Unless your name is actually "Facebook Chat", of course.
Quick answer: use userid@chat.facebook.com without SSL/TLS. If you don't have a userid you need to create one and log out of Facebook and back in again first.
My friend lists correspond to privacy settings, not human-friendly groups (just photos, nothing, professional contacts). They should divorce friend lists from chat groups.
