Yeah, there's 2 levels of it.
Omegatron is talkng about when an Admin sets a user up as Ignored by the whole site. They could log out, or reregister, and see that their posts weren't there. You could link this to the IP address similar to how bans are done. It's not perfect, but better.
Dslam is talking about a user choice to ignore somebody. If Omegatron doesn't want to read my posts, he could ignore me. He would only see the single line placeholder that 3dshroom mentions in place of my posts. Everyone else would see my posts.
