Starting today, if you have an Amazon Echo and an Ecobee 3 connected thermostat, you can change the temperature of your home by just barking commands at Amazon's connected cylinder. The $249 Ecobee 3 is the first thermostat that works directly with the Echo, allowing you to set specific temperatures or just turn up the heat with simple voice commands.
Other connected thermostats, such as the Nest, can be controlled with the Echo through clumsy IFTTT recipes, but I can tell you as an owner of both the Echo and a Nest, they are not very convenient to use. Direct control, as is afforded by the Ecobee, is much simpler and doesn't require special vocabulary to make it work. The Ecobee 3 was also the first thermostat to gain compatibility with Apple's HomeKit, which allows for voice control through Siri on the iPhone.
The new Ecobee Echo integration can be set up via Amazon's Alexa smartphone app now.