Since everyone will have weighted voting power, all you will have to do anyway to game the system is upvote anything with a lot of votes. Steadily build up your karma with this bandwagon method, and then bam spring some ad-infested blog spam upon everyone.

This can be accounted for by giving more weight to those who vote for a story early in its accumulation of points. The biggest voting power boost is given to someone who gives a story its first point.

Presumably, however, if someone who did that started voting for "bad" stories, his voting power would, appropriately, go through the floor.

My guess is that these self interested folks would create many accounts, buy cred with mischievous modding, and make a distributed effort to upmod a particular story. They wouldn't do this to upmod any random story. But news.yc needs to get much bigger in order for this to be a real problem. This is a real problem on Digg.

I'm pretty sure separate accounts are linked via IP addresses. And the one person who will go to all the trouble to spoof his IP address consistently for each of his 10 accounts isn't worth worrying about.

We're small, and we're going to stay small for awhile (hopefully), so this really isn't worth worrying about.