Since you've got some experience with it, do you have any idea how hard/easy it'd be to get an iBeacon working from a Raspberry Pi equipped with a Bluetooth dongle?
I used Apple-provided bluetooth capabilities so my experience is probably not particularly relevant to Raspberry Pi, sorry. One thing to think about is battery life, unless you only need to pair the broadcaster and the receiver once. What I mean is, if you have a listener that is constantly scanning for a signal and doing some logic depending on the signal strength, you are bound to have battery life as your biggest challenge and potentially a deal breaker to any real use.
It should be straightforward with BlueZ 5. Good luck finding documentation on how to do it though.