Security system using bluetooth phone as a key

What Im trying to make is fairly straight forward, Im just not sure what I need to make this a reality... I'm guessing an Xbee and Arduino board..

Basically what I need is something that will trigger a relay momentarily when a paired Bluetooth device (a phone for instance) is detected, and a second relay to trigger when the device (phone) goes out of range. Any Ideas?

I'm guessing an Xbee and Arduino board..

No Xbee is not bluetooth.

You need at least a bluetooth module or a bluetooth arduino.

http://www.arduino.cc/en/Main/ArduinoBoardBluetooth