I blogged about hosting a grief-free Terraria server. I don't have comments, so I'm taking questions and other bits of discussion here. I can probably point you in the right direction if you need specific advice on a topic too, but I'm not going to be writing plugins for a lot of these features (at least, not yet). Part of the point is to get people thinking in the mindset of "the anti-grief plugins will always have weaknesses" and to work around them. The sad truth is that no system can perfectly detect hacked clients, and even then, you don't need a hacked client to grief.