The Lockitron is a device that attaches to the deadbolt lock on a door and allows it to be opened and locked on smartphone control. It uses WiFi to connect to the Internet, making it accessible from anywhere else there is an Internet connection. Newer iPhones can also connect to it by Bluetooth, allowing automated unlocking when you approach the door while carrying your phone. An API exists for interfacing the Lockitron with other devices.
After some earlier models, the latest Lockitron was launched via a "Kickstarterish" campaign not actually conducted on Kickstarter (which rejected it due to stricter rules they have imposed about what sorts of things can be launched there), where people made advance pledges to purchase the model (though no up-front cash was collected). A year later, the cash was collected and the shipments were supposed to start, but they have been plagued with delays due to technical problems. It did ultimately ship, however.