Since PR1.2 my N900's battery was lasting for 2 days max, in standby mode and 1 day with low usage. And that is with 2G and no GPRS data transmission. I'm almost sure that the problem was hildon-desktop.

On my device it got stuck at 4-5% all the time. That figure seems to be low, but it does help to drain the battery.

On some other thread here at T.M.O I've found a hildon-desktop package with a fix. (sorry but i don't know from memory where is it). After installing that, hildon-desktop stays below 1%. I can run the N900 in standby for as long as 5 days! Usually for 2 days with moderate use (a few calls and many minutes of wifi, browsing and easy-debian).

I also have Titan's power kernel, but without overclocking or underclocking. I also have half of the extras repository installed.