Tutorial is here. When that webinar was recorded, only the iPhone app was available, but the Android app is now live and works the same way.

I tried it yesterday and got right at 5 hours before my phone battery died. I've got a HTC Incredible (first generation) with an aftermarket slimline accessory battery that I think is 1750 mAh (but I can't find the specs, and I don't feel like taking my phone apart to check, at the moment ).

I'm still considering options. An accessory battery pack, or a wider high capacity battery, would be lighter (and less expensive!) than a whole new SPOT device. Of course it still wouldn't provide the check in and 911 options that a SPOT does. And I'm not sure whether the phone live tracking will work outside of cell range, but I have to assume it won't, since the phone can only receive satellite signals, not send them.

But I wanted to throw that out there for anyone who's interested.