It's now decidedly easier to control your home security system if you have an Echo speaker or another Alexa-powered gadget. Amazon has enabled a Security Panel Controller framework that lets you control security systems with your voice. You can arm or disarm them, specify certain modes (home, away and night) and simply check in. And yes, Amazon is well aware of the security implications. You have to manually enable disarming by voice, and you can specify an Alexa-specific voice code instead of shouting your PIN code to everyone within earshot.
The functionality is available now in the US, and companies like Abode, ADT, Honeywell, Ring and Scout Alarm are already using it. It's understandable why you might hesitate to use Alexa support, especially if you're concerned that someone might listen in. Amazon is clearly betting that its own security measures (including user-specific voice recognition) are enough, though, and this could be convenient you'd rather not pull out your phone or walk across the house just to punch in a code.