There are technically 2 levels of ignore.
Arsin is using the default, most basic level which puts a placeholder where the post would be to let you know that you're ignoring that person. It has an option to show the post anyway (in line) in case you're just faking because you're a poser bitch.
You can enable pignore (power ignore) in the User CP to basically remove that person from your posting experience (save quoted posts by non-ignored users). This is sometimes on by default, and sometimes not depending on what version of vB we're running, what changes were made to the User CP lately, the phases of the moon, etc. I think it's set to "off" by default now.
I don't ignore anyone, for the record.