Initially, I used the trick Jordi mentioned to drop by idle consumption down to about 5 mA, which I'm OK with. But after deciding to reset my phone (actually a couple times; there were some configs I wasn't happy with), MeegoTouchHome finally agreed to play nice and I haven't had to mess with my home screen since my last reset; I idle at about 7 mA now.

As for draining the battery, I'm actually seeing conflicting information about fully discharging Li-ion batteries at the end of the "Ideas for good battery life on N900 and N9?" thread in this forum. This seems to be backed up by a couple different websites I found:

How Stuff Works, Battery University, and *gasp* Apple.

I'd assume that Apple's situation is closest to the N9's since the battery in iOS devices isn't user replaceable, and it'd be in Apple's best interest to avoid making users get new batteries. Of course, I suppose it could be part of their devious plan to milk more money out of Apple lovers.