Aaah yeah the power kernel is a great tool for helping out with battery life. Especially when running low on battery a heavy underclock (down to 125MHz) and loading the low voltage profile really does help scrape the last few miliamps out of the battery. You have to put up with sluggish performance doing that of course but it's allowed me to have the phone last a night out with very minimal charge on a number of occasions.

Oh, and BTW, doing a bit of reading I think I've discovered the cause of my rapid battery failure. Low temperature. I left the thing on a window sill that turned out to be very cold while visiting some family and it was afterwards that it couldn't hold charge properly anymore. I think it must have been outside of the normal operating temperature for Li-Ion batteries as being too cold and discharged is not something they like!