I think he means OSX, which has in fact had this functionality for a number of years now.
I think you mean every email client in existence, which has had the ability to send SMS messages through the carrier's email to SMS gateways for as long as those gateways have been in existence.
I've used Forte Agent 1.93 (windows) to do this all the time. A few years back they blocked this ability (at least the the IP's I was using).
SMS Gateways: http://www.email-unlimited.com...