More on NFC's etc...

This article goes more in-depth into NFC technology and other interesting stuff about cell phone credit cards.

http://www.amonline.com/publication/article.jsp?pubId=1&id=16096

How they work

You may be asking yourself...how do these cell phone credit cards work? Well, they utilize a technology called near-field technology. It is explained in the article here;
http://electronics.howstuffworks.com/nfc-phone.htm