Been working on a project that involves iBeacons as of lately. Thought I'd share some of my notes here.
Warning: Developer lingo ahead
Discovered somewhat late in the game that you CANNOT search for any and all available iBeacons in the area. You have to know the UUID before you can interface with an iBeacon. Thankfully, the manufacturers of these iBeacons have been using consistent UUID's and just changing their Major and Minor values of their beacons. I've compiled a list of common UUID's, which in theory could be used to search for available Beacons. Note: I'm not sure about each of these items, but I have verified that Estimote is correct. If you have experience with any of these UUIDs or any that are not listed, please let me know in the comments.
Raspberry Pi: E2C56DB5-DFFB-48D2-B060-D0F5A71096E0