Currently Google Talk supports non standard (isn't even accepted) proto XEP called "Presence Queueing":
It's intended for enabling power saving mode in XMPP clients for mobile devices, and offers a real benefit for power saving.
Facebook's server offers a similar feature, using a different mechanism:
Does Ejabberd provide anything like that, or may be it supports Presence Queueing which looks like a promising proto XEP?
I'm in the process of trying
I'm in the process of trying to get this working for my xmpp domain too.
I have done a bit of research, and found the following:
* The xep link that you have given is broken. If you have an updated link, please share. Otherwise, I will talk to DC and ask him to fix his website.
* I have also heard rumours of Facebook supporting a similar extension called "sleep" () that might solve the same type of problem. I will evaluate this over the next couple of days too, and report back.
* m-link (server implementation behind jabber.org) already supports this extension. If you "evaluate" m-link () and/or buy "standard support", you should be able to get this feature working on your domain *today*.
* If you don't want to use m-link, I will probably have a go at implementing this in ejabberd over the next month or so (and I will submit patches upstream when I'm done).