Apple's ambitions for NFC are apparently broader than just wireless payments and contact exchanges on the iPhone 5. According to Cult Of Mac's anonymous source, Apple is planning to use near-field communications with updated Mac computers, basically turning any Mac into a near-identical version of how your own machine is set up. The system would use the iPhone as the authenticator, with user data potentially being stored on both the handset and in the cloud, and give access to the address book, passwords, desktop settings, bookmarks and more.
"The Mac authenticates with the iPhone, which contains a lot of the information the computer needs, such as bookmarks, passwords and other data. The system would essentially turn any Apple computer into your own — like you’re actually working on your own computer. Same settings, look, bookmarks, preferences. It would all be invisible. Your iPhone would be all you needed to unlock your Mac.
Address book would show their contacts, and the user would have full access to their information in the same manner they would if they were working from home. This same behavior extends to even showing the same desktop picture, mouse and keyboard settings, and would eventually extend to software licenses and passwords for websites such as Facebook." Cult Of Mac source
When the iPhone is removed, the system logs out and returns to its previous state, with no record of your own files, passwords or settings. Apple has apparently been working on the system for some time, though it's still unclear whether the project will reach a commercial roll-out. Recently the company was tipped to be working with SIM experts Gemalto on an NFC-enabled embedded SIM for the iPhone that would allow for high-security authentication together with easier carrier switching (as long as your choice of carriers had been approved by Apple beforehand).
"This functionality is extended to access a user’s home folder, which will be stored and accessed either through storage on MobileMe or by using the Back to My Mac feature to connect to the user’s home folder."