Does the battery level drop gradually or is there a sudden drop to near-zero? The latter would indicate a worn-out battery.
I don't think any of the "userland" packages would have an effect on battery life, so if there is a problem it's probably on the kernel or X server. Do you feel like downgrading to the Nokia versions (kernel-diablo-flasher=2.6.21-200842maemo1 & xserver-xomap=1:1.3.99.0~git20070321-0osso20083801, note that this will uninstall osso-software-version so you'll have to re-install it manually after testing) and comparing battery life?