This feature is only available within Android 5.0, however, and the pool of devices running Lollipop at the moment is pretty much limited to the Nexus line.
Although it is only available on Lollipop, I find it pretty neat that these features have native support. The caveat about setting a trusted place to unlock is straight out of Tomorrow Never Dies[0]:
"Be aware that location signals can be replicated or manipulated — someone with access to specialised equipment could unlock your device."
"Be aware that location signals can be replicated or manipulated — someone with access to specialised equipment could unlock your device."
[0]: http://en.wikipedia.org/wiki/Tomorrow_Never_Dies