Sigh , yet another nail in the XMPP coffin, at least as far as the general public is concerned. Remember when we had ICQ, and AIM, and MSN Messenger, and Gadu-Gadu, and we were dreaming of a unified messaging system?
It's worth noting that XMPP was based on XML. New hotness is JSON, or maybe even compressed binary protocols.
SMTP survived despite changing fads. If we're ever going to standardize IM (or anything), we have to accept that protocols may use older technology. Someday JSON will be old too. Let's not make these mistakes again.