SelfieType is a project out of the Korean giant's C-Lab startup incubator, which uses the front-facing camera to track your motion. Prop your phone up as if it was a display, fire up the app, and then touch type onto the table as if you had a keyboard there. The phone's front-facing camera and a "proprietary AI engine" will then examine the motions of your fingers, interpreting them as the taps on a QWERTY keyboard.
Naturally, skilled touch-typists only need apply, since there's no real guide for where your hands need to go in the real world. At least right now, since the team behind SelfieType hopes to make it easier to use, and more intuitive for novices in the near future. Unfortunately, I wasn't able to try the system for myself, and was only able to watch a canned demo by one of the team.
But even watching from the sidelines, it's clear to see the potential such an app has, both for emergency typing when you need to be faster than fingers on glass. You probably won't expect to see this pop up in the next Samsung phone, but if the company feels that it can make this ready for prime time, perhaps it'll do so in a few years.