Douglas Rushkoff writes an interesting article on Mobile Internet site "The Feature" that points out fascinating possibilities for the way we pay for things this century, all using our mobile phones (which are, after all, a network of wireless computer devices) and "complimentary currencies."
Handheld wireless technology stands ready to enable what's known as the "complementary currency" movement in ways so powerful that the dominance of national currencies such as the dollar and the euro may soon be called into question.
What if we could use our cell phones to confirm transactions with one another as simply as pressing a button? We don't even need to shake hands with each other, only with the central server, which can confirm that both parties have agreed. As Paul(Paul Hartzog) put it in an email, "enabling the back-end for a truly decentralized marketplace with buyers, sellers, traders, and sharers is the open-source 'killer app' of the next century."
An interesting thought and well worth the read.
TheFeature :: Open Source Currency
You may wish to read the article in Internet Explorer. There seems to be some issues with the page's CSS in Firefox (at least at my screen resolution there was).