It’s an accelerometer. You can already do the simplest form of this with SmartThings and one of the accelerometer sensors, it’s the basis for one of the knock recognition SmartApps. They’re adding some kind of pattern recognition so you can have different knocks mean different things.
Some thoughts:
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Devices in the kickstarter phase that have a “technical specifications” link that just takes you to a glossy picture of the prototype and never give you any real technical specifications are not likely to ever work the way the marketing material promises. Just sayin’…
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if you dig deep enough, you’ll find that they’re claiming they can run a daily use Wi-Fi device for 12 months on two AA batteries. Which no one else in the world has ever been able to do. This establishes the level of credibility for any of their other claims.
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Lockitron removed basic knock recognition on the second model of their lock for the simple reason that it turned out there were too many local variables to be able to sell it in a mass-market. It did work great on some doors and some conditions. Others were too sensitive. Many didn’t recognize the knock at all. The same issue applies to the smartapp that does doorknock recognition. It does work for some people. It doesn’t work reliably for enough people to be the basis for a commercial product.
This is one where I would definitely wait until it was in regular release with normal consumer protections. The odds of this working as promised are very small. I’m not saying it’s impossible, but I would’ve liked to see a lot more about this patent pending technology before I considered it a credible product.
My basic rule applies: no device is real until you can order it for two day delivery from Amazon under normal consumer protection laws. Up until then, it’s all marketing. 
The following topic about the doorknocker smartapp discusses many of the issues with accelerometer vibration sensing.