Qualcomm wasn't about to just let Samsung and Nvidia own that portion of the tablet market that is stylus-enabled. Samsung has been the dominant player in the stylus market for years, because they were the only ones to make pens that actually worked accurately enough to be useful for handwriting and drawing on a tablet. Pretty much all of the "capacitive styluses" are no better than our fingers, so having something that works like a real pen on a tablet was a huge improvement over the other solutions out there.
However, we haven't really seen anyone else challenge Samsung in stylus-enabled tablets until Nvidia showcased the Tegra Note 7 this year, which introduced a different technology directly into their Tegra 4 chip, which made it possible for the screen to capture data from the stylus much more accurately. It was also a much cheaper solution, since until then we didn't see any "Note" device that didn't start out at $400 or more. The Tegra Note 7 only costs $200.
It seems Qualcomm doesn't want to be left out of this market, and has not only done something similar to Nvidia, in the sense that it's a new technology being integrated with the chip itself, but they've also innovated by making the app you're using capture the design you're drawing for example, not through touch, but through ultrasounds.
The best part about using ultrasounds, it that it doesn't even seem to need to use a stylus on the tablet, and you could even use a regular pen to draw on a piece of paper next to the tablet, and the microphone inside the tablet will pick up that sound, and then the chip will process what it's hearing into whatever you were drawing on the tablet. This most likely needs apps to be compatible with this method, though, so when Qualcomm will be unveiling this technology at CES in a few days, they'll probably announce that they will have an SDK for it too.
It's interesting to see that we'll have 3 different stylus/handwriting/drawing technologies. One is Samsung's digitizer based technology, that uses a sensor to see where you're moving the pen, and then it writes or draws on the tablet, as if you were actually doing it with the pen. Then there's Nvidia's "DirectTouch" technology that captures the pen touch in a super accurate way, and now it seems that we'll have the ultrasound technology, that writes or draws through the sound your pen is making when touching a surface, and not necessarily the tablet itself. There should be some interesting times ahead for people who love tablets they can write or draw on.