In conjunction with the free Kevo app, you can send out an electronic key to friends, family and loved ones who don't have a key to your house, but do have a compatible smartphone. This temporary key only will work for a limited period of time. And since Kevo is also a mechanical lock, if nothing seems to work, you can still use a regular key to get in the house.
Two AA batteries will keep the lock operating for about a year. While there is no precise launch date or pricing information available, you can register your email address with Kevo to receive notifications via email. To do so, simply click on the sourcelink.
source: Kevo via TUAW