The basic premise behind a smart mirror is a 1-way mirror sitting atop an LCD screen and camera. When the LCD projects bright enough light the person standing on the mirrored side will be able to see it alongside their reflection. The possibilities are incredible and almost entirely software-based.
This Kickstarter is taking things beyond simple smart into entirely new ways to interact with technology. Winking and smiling are “gestures” that the mirror can interpret and use to trigger an action. Face recognition can keep multiple users separate.
I had wanted to build my own smart mirror (and I still may), but I can say with confidence that $179 is a really reasonable price for a really interesting piece of technology.