Wired's Steven Levy on a $130 talking smoke detector.
Nest Protect also knows when a warning isn't necessary. By analyzing sensor data (things like smoke, heat, and carbon monoxide levels), the system determines whether a situation is something to be concerned about. Eventually, having users specify where in the house the device will be installed could play into it too. If a unit is in the bathroom, its sensors could understand that the steam from a shower isn't anything to warn people about. The devices have the capability now, but Nest has to wait on regulatory changes to activate them. And because Nest devices are connected to each other by Wi-Fi, the voice can also tell you where danger lies. If there's a problem in the kids' bedroom, every device in the house will tell you just that.
It's easy to approach this with a wary eye — a thermostat is real chore to install and Nest's smarter replacement can save a homeowner serious money, whereas a smoke detector is $5 and you can just slap it on the ceiling. When you factor in false "burned toast" positives, the hassle of tracking down whichever one is chirping incessantly, and the fact that these guys are making nice versions of ugly-but-ubiquitous household appliances, maybe? I feel like their gameplan, ultimately, must be to fix the maddening, wallwart-carbuncled, powerstrip-knotted household power distribution situation.