Update...

I did a complete reflash of my n900 (eMMC & FIASCO) to PR1.3. Fully charged it, turned off wifi, gps, bluetooth & let it sit idle. Battery was dead in a few hours.

Then I installed only i2c-tools to get power measurements from powerscript.

The problem remains:

On charger, system pulls 0-50mA. As soon as charger is disconnected, it constantly pulls ~350mA and stays nice & warm.

If left idle, according to top, CPU use stays at less than 5% in both cases, 0% io, 0% irq. Batteries still drain in <4hours.

I tried installing the batterypatch for the non-power kernel, but it had no effect.

meh... is this just something I have to accept?