Battery life of my HP mini with WinXP: 3-5 hours, depending on use. (I hear Win7 is better.)
Battery life of my HP mini with Fedora 11: struggling to get one hour.
[Ed. later: should have mentioned that this is having done everything powertop suggests. Top culprit seems to be hrtimer_start_range_ns, which is much discussed but has no solution that I can find.]