Following the recent withdrawal of their AndroidIBeaconLibrary product, which provided Android devices with an invitation to the iBeacon party, Radius Networks have revealed a (sort of) replacement solution.
Their AltBeacon initiative provides an open source specification that provides very similar functionality to Apple's iBeacon spec, but without violating Apple's IP.
There's more on this, including an interview with Radius Networks' CEO, over at beekn.net.
Getting up to speed should not be a problem for anyone familiar with the iBeacon spec and, true to Radius Networks m.o. examples and source code have already been made available (accessible via links on the AltBeacons home page).
Interoperability is key for me, so I'm looking forward to extending the iBeacon Scanner app to accommodate AltBeacons alongside iBeacons...maybe it's time to drop the "i" from the app name too? ;)