As a developer, one of your primary concerns should be the vulnerability of your iBeacon profile. It's very easy for anyone equipped with a Bluetooth sniffer app to determine your beacon signatures and spoof them in their own app. After all, you've already made your iPhone act as a beacon during the course of this book.
The Consumer Electronics Show (CES) 2014 offered its visitors a treasure hunt powered by iBeacons and before the conference even began, the show had been hacked by the team at Make Magazine so that they could win the treasure hunt without even being at the event. Read more about Make's audacious hack at http://bit.ly/makehacks.
What Make Magazine did is downloaded the Android APK file (a compiled zip containing the Android app) and ran it through a decompiler to discover the beacon profiles used by CES.