Same problem here.
Always 12%-17% of CPU (IDLE, charging... always 12% as minimum CPU usage).
First, I thought in "swappolube" (and after uninstalling it, ONE battery cycle the phone worked OK, but after changing, the issue was back again).
Then I uninstalled Flashlight add-on (the one that allows you to chosse between cam and light when opening lens cover), but nothing.
No more new software installed before this issue, perhaps some update for some app?
I disabled my loved theme "black plastic" (updated very often) but nothing again.
I will try uninstalling FileBox and MediaBox, the apps more often updated here, perhaps then... I don't know.
It's annoying to see my N900 with less than 6-8 hours of battery WITHOUT ANY USE, no phone, no lan, NOTHING, but battery gone (Xorg, ohmd, and a few more eating battery every second)



left: normal idle usage
center: activity usage
right: "new" idle usage!!