[codys]

Any one aware of the technical details of how this was accomplished?

Is listening for other BLE transmissions low power enough that it can be done while keeping the claimed "several years" battery life, or is there something extra going on to limit the power cost of listening?

Is the protocol between the beacons themselves actually BLE in the mesh case? Or do they just expose that to phones?

Are the beacons establishing BLE connections for the mesh, or are they just taking advantage of announcements (which would likely allow avoiding some power consumption as long as the message is small)? A mix?

[jimiasty]

Beacons use only BLE to talk to each other; there no Zigbee or other connectivity technology. That way both phones or other beacons/BLE devices can inject data to mesh.