I've been using a MiCasa Verde[1], alongside the compatible KwikSet Deadbolts[2], an android app called Automator to accomplish the same thing. It's actually a little pricier but you get:
a. Remote entry -- unlock your door from afar. b. A nice home automation system (mine's expanded to control lights and thermostat now) c. Keypad and key-entry as backups
I love it. Being able to remotely lock and unlock your doors is super handy, whether it be for guests, contractors or what not. But what's really handy? Never worrying about locking yourself out of your house again.
If I could just get rid of my car key, I'd be thrilled.