To add a bit to the confusion, I found out that the percentage reported by lshal sometimes goes up again! I'm using the desktop command execution widget to see my battery percentage and at a cetrain moment it was 18%. Then I refreshed half an hour later or so and it was at 25%! Again 2 hours later of almost no usage at all, it went down to 20%.
So maybe the kernel battery measurement is a bit off?
On the other hand, my battery life is great. I get 4 days out of it, while being wireless online from time to time (30 minutes by day tops), only 2G and wireless switched off when not used.

Franky