Wikipedia
Lockitron is a device which can lock and unlock deadbolt locks via remote control, typically a smartphone. The device is made by Apigy, a start-up based in Mountain View, California.
The device fits over the lock control mechanism on the inside of a door, and the door can then be unlocked via an app on the phone, or via web page control. Phones with Bluetooth Low Energy (4.0) can also automatically unlock a door when an authenticated device is nearby. A supplied NFC tag can be read to trigger a command to toggle the state of the lock.
Virtual "keys" can also be created for guests or repair contractors etc., which allows access to the home. The virtual keys can be distributed over the internet on demand, and can also be revoked on demand. The door can also be locked or unlocked via an SMS "key" for those without smartphones.
The original lock continues to work with traditional keys. When a traditional key is used, the device can send a notification to a smartphone.
The device also exposes a web-accessible API, and is built around an ATMega microprocessor meaning that it is Arduino compatible for other custom behavior. Lockitron also supports integration with Doorbot, a doorbell system that sends video and voice from the door to a smartphone. It can also integrate with Lumawake, and will automatically lock your doors when Lumawake detects you are asleep. Other devices that have promised integration with Lockitron include the SmartThings Hub which will lock or unlock the device based on preprogrammed rules and the Pebble Smartwatch which will connect to Lockitron directly over Bluetooth Low Energy to use the Pebble watch as a key.