twitter/identi.ca/etc: XMPP and SMS

I think SMS gateways should be just another XMPP client for twitter/identi.ca. Telephony providers could implement them and charge their users (that also may happen to be existing clients) for the SMS sent and recived. It makes so much more sense, instead of having the service pay for them!

Could this be twitter's plan? To charge telcos for the right to access XMPP?