According to The New York Times, the Samsung Galaxy S4 will track a user's eyes to enable scrolling on webpages. Their source, a Samsung employee who spoke on a condition of anonymity, says that software will take a precedence over hardware in the upcoming Galaxy S4 device.
Samsung has filed for a trademark of "Samsung Eye Scroll" in the United States back in February. The device will track a user's eyes and use that to determine where to scroll. Imagine finishing reading a paragraph on a webpage. When you're eyes reach the last line, the device will automatically scroll to the next paragraph.
This isn't the first time that Samsung has employed eye tracking. Their current Galaxy S3 device makes use of the feature called Smart Stay to know not to dim the screen when it's being looked at. We'll hopefully see this feature demonstrated at the press event on March 14, though it hasn't been confirmed that it will be making an appearance.