I've bought the machine, so here are my own results.
Thanks to all of you, your reports and my results are very close. With very light load, like Vim, I can get 9 hours of battery life. When I do browsing, changing between apps a lot etc., but still nothing particularly CPU-intensive, it can manage about 7.5-8 hours. Based on wattage measurements, severe load, like e.g. playing Diablo II on wine would drain the battery in about 5.5 hours, but that's an extrapolation.
If you are a Linux user, and you want extra hours for free, use
powertop. It's a tool that besides measuring CPU wakeups per seconds, is able to fine-tune a number of power saving options. Including the single most important one, SATA power saving, enabling which saves about 0.7 watts. By comparison, disabling an idle Wifi saves 0.3 watts only.
If you need time, watch the watts,
gnome-power-statistics are both good. The latter seems to be a bit off, it shows values about 0.5 watts lower than what can be calculated by multiplying ACPI voltage and current values, still, it has a nice graph.
What you won't be saving much power with, so don't even bother:
- turning down the HDD
- disabling X or GNOME, at least on contemporary distros (I use Ubuntu 9.10)