Mobile Commerce has started picking up in Asia now, though still selectively. Here you are able to pay on vending machines and automated ticket counters by sending text messages from your cellphones. Your cellular phone companies act as the creditors / intermediaries between you and the vending companies.
This process of payment would become more popular once you are able to carry your mobile phone to other countries. As the telecom Industry worldwide consolidates, you would be able to use your mobile phones in different countries without changing a SIM card and seamlessly without needing your telecom company's help.
That would be a time when many more vendors would start accepting mobile commerce based payment systems.
Also, upcoming technologies like Vanu would make telecom transmission being done thru the software in your handsets. Eventually, it would lead to changing telecom companies a matter of downloading an exe file, rather than changing a SIM card or changing the handset (from GSM to CDMA network).