In the interest of being nice to new players...
On the FAQ page for Meta only, since it's bit of a different beast than the others, the verbiage talking about downvotes:
If you post something that's off topic or incorrect, it will be voted down: you lose 2 reputation points.
Should include a quick blurb about getting downvoted for people not agreeing with the question / suggestion / proposal / ...
If you post something that's off topic, incorrect, or that those in the community generally disagree with, it will be voted down: you lose 2 reputation points.
Before you flame me, consider: This should help to curb "WTF, why did this get downvoted" comment wars thus reducing the load on the site.
Ok, now you can flame me.