@Friendica Day I made a friendica addon that adds a Facebook-like chat using Jappix Mini. It's probably not very good code, but I hope it works out somewhat. Would be great if you install it so that we can try it in practice!
No, the addon has a cron hook that tries to get the jabber addresses from the friendica sites of the contacts, but this does not work yet unfortunately... I'm working on it A profile entry for XMPP accounts would be very useful I think, but I tried to get it working only as an addon without modifications of the Friendica source.
The discovery thing is probably not worth trying very hard. I've got Friendica and XMPP on the same machine, but on different subdomains (and I'm using different nicks, too). Other people won't even have their XMPP accounts on the same machine, especially those on shared hosts.
This is well worth a database/profile entry, isn't it? @Mike
Somebody said "as soon as the last missing features (most important chat and liking comments) are implemented the people will start to switch." and I was able to say "Actually, I've just installed chat".
(I promptly broke it, but that's besides the point).
It needs a little work (move the BOSH field to the admin panel, get the button themed), but this is a great little addon already.
@Leberwurscht Brot I understand the discovery mechanism now. It's simple, but ingenious and doesn't interfere with anything that is already there! But I do agree with Thomas' suggestion that the BOSH setting should be an admin function. As far as I can see, any changes the user makes here depend on the admin's support anyway. Isn't that correct?
I'm going to rework the existing XMPP documentation - suggesting it as an alternative for people who want more flexibility. Then I'll write a new how-to for the new plugin, as soon as it becomes official.