I don't think it's hype at all. Remember money, and joins (and not to mention transactions) that occur from SMS is not something something to disregard. If you are planning on implementing SMS billing I suggest you look at
www.GXBill.com www.Netbilling.com www.localbilling, and
www.passwordbyphone.com they are the biggest and best in the adult industry.
After you have implemented your SMS the next thing to consider is localizing and translating your site/s if this is something you are interested in. Feel free to contact me at omar at globallytranslated dot com