If a person is to be truly invisible then there should be no way to establish that they are online or eve exist on the system.
Thats the point I'm trying to make though....you _can't_ establish which invisible users are online. Take this forum as an example...there are about 12,000 users....if there are 2 people online and one is invisible, are you telling me you could tell me which user it is?
Currently an invisible user is shown in the "list" but the tag "invisible" is added to their information line. This is not an invisible user.
I think you may be taking "Invisible" in a different way than intended. I don't think invisible means you should be non existant, it just means you can't be tracked.