EDIT: The library below has been moved here:
https://github.com/AltBeacon/android-beacon-library
I have ported the iOS7 iBeacon SDKs to Android, and was able to see standard iBeacons and estimate their range. The code is available here:
https://github.com/RadiusNetworks/android-ibeacon-service
For this to work, you need Android 4.3 which introduced the Low Energy Bluetooth APIs. You also need a device with a low energy bluetooth chipset.
If you don't want to use the full library above, you can roll your own. iBeacons simply transmit a BLE advertisement once per second that start with a known sequence of bytes. You simply have to tell Android to do a BLE scan, get each advertisement, and look for one that starts with the known iBeacon byte sequence. You can then parse out the iBeacon fields. Here is the code the shows how this is done: