The main battery drain I have seen is yesterday when I had a Fennec/Firefox process hang and take up 99% of the CPU. It ate most of my battery in under an hour. I had put it back on my belt and the next time I pulled it out, I noticed that the device was warm to the touch, and fired up conky to see if anything was eating the CPU. Sure enough, there was that stray Fennec process...While I prefer tabbed browsing instead of opening multiple disparate windows, I am going to be very circumspect about my use of Firefox for a bit, or I'll use iceweasel from Debian...

--vr