EDIT: This is now possible in Android 5.0 and to a limited extent in Android 4.4.3+. See here: https://stackoverflow.com/a/25035954/1461050
Unfortunately, this is not possible as of the latest Android 4.4.2, because Android does not support BLE peripheral mode needed to advertise as an iBeacon. See here for details.
The good news is that peripheral mode support has been added to the Android open source project, so this may be possible in a future release, perhaps Android 5.0. While Google has made no announcements, look for a release in June 2014 during the Google I/O conference.