[claudius]

They are still supporting XMPP for c2s connections, though; i.e. if you are on a phone, you can use XMPP to connect to Google. What they don’t support is s2s, which – unless you somehow run your own XMPP server on your phone – has nothing whatsoever to do with mobile :)

FWIW, they could “easily” build a mobile client that connects to Google via some nonstandard protocol which preserves energy on the phone while being mapped to the standard XMPP protocol from Google onwards.

[MattJ100]

Funnily enough, that's exactly what they did do, back in 2008 :)

Originally Android included an XMPP API that applications could use to connect to Google and other XMPP services. This got replaced by a Google Talk-specific API at the same time they switched to a proprietary protocol.

E.g. http://blog.kosmokaryote.org/2008/02/google-cannot-be-my-cha...