In a recent patent filing "Multimedia data transfer for a personal communication device," Apple is offering text messages without the GSM SMS protocol, or even the need to read.
While SMS requires an intermediary server between sender and receiver, Apple's patent has a sender's device convert text messages to an audio signal with this audio signal getting passed through standard audio communication channels (reminds me of faxing, really). This signal can then be translated to actual language on the receiver's end, with a speaker reading the message back. Potential listed uses include texting for the blind and for those with very small screens.
iPhone Nano, anyone? [macnn]