Starting with demo code and hacking the extension library, I'm now at the point where I have the Moteino's RFM69 constantly in Listen Mode such that it's in Rx for 1ms out of every second, with the arduino asleep. Setup this way I estimate average current consumption is about 16uA, or about a 1000x reduction, as compared to having the radio in Rx mode all the time. There is additional power savings from keeping the arduino in deep sleep rather than having it wake up every 8 seconds. I could reduce power consumption by an additional factor of 67 by stretching out the idle period between Rx windows to 67 seconds, but the tradeoff would be greater latency in responding to commands. For some applications, like weather sensors, that may not matter. For some remote controlled applications, though, it would be too long. Either way, Listen-Mode can serve the purpose of an ultra low power wake-up radio, if so desired.
Now that I have address filtering turned on, I'm hoping I can lower the RSSI sensitivity threshhold and thereby gain back some range. At least in my view, the two biggest selling points for the RFM69 radio (and thus the Moteino) are range and Listen-Mode.