Make posted this video showing off their latest DIY project that uses an Apple Watch to open an electronic door lock wirelessly with the tap of a wrist. It uses an RFduino module to communicate with the Apple Watch over Bluetooth, integrates with existing door and security systems, and uses custom iPhone/Apple Watch apps.
Now that Apple’s HomeKit platform for home automation accessories is a real thing, it’s likely that we’ll see solutions like this in the future that won’t require the DIY build apart from installing a door lock accessory. Although there are some limitations with HomeKit regarding providing access to a home for security purposes. This solution, however, is an option you can do today for around $100 per door and 12-16 hours of work.
More details on the build at Make.