Fingerprint scanners on computers and smartphones are a not a new thing. First devices have been on the market a decade ago. Problem was that they did not work reliably. If Apple managed to develop a fingerprint scanner for the iPhone 5S that works every time than there will be a massive Fingerprint revolution in consumer electronics.
I know many people that enter a passcode every time they pick up their smartphone. It helps secure your device, but it is a big pain in the butt. Apple is seen to solve this pain with the introduction of a fingerprint scanner in the iPhone 5S. There have been fingerprint scanners on laptops and smartphones before, but they have not been reliable and degraded quickly.
If Apple solved the fingerprint sensor for smartphones than we will see a fingerprint scanners rolling out to all personalized consumer electronics. If Apple did not do their home work on the fingerprint scanner, the company sets itself up for a PR disaster.
A horror scenario would be for instance if the fingerprint scanner could be easily hacked. Let's hope for Apple that they developed a robust, reliable and secure fingerprint sensor for the iPhone 5S. The Wall Street Journal has some background on the topic as well here.