nueMMS will let you send MMS over e-mail, so you won’t need an MMS gateway to send MMS. It supports several providers/carriers, and you can add more carriers in carriers.nuemms – its a simple xml file. It also supports sending your gps coordinates over mms (..kind of untested, but give it a shot).
Source
This article is over 2 years old — the linked page may have changed, moved, or been taken over since then.