After a meeting with a component supplier, analyst Brian White of Topeka Capital Markets wrote that the iPhone 5S and iWatch could include a fingerprint scanner.
A fingerprint scanner would allow Apple to secure iDevices and implement a secure payment method using credit cards.
The same technology could be implemented in the iWatch and users could use the watch along with a software from iDevices in order to make safe payments or to secure their handsets.
The iWatch is expected to be interconnected not only with iDevices, but also with the future Apple iTV, but nobody knows yet how this will be done.
Source: Apple Insider