What 'Nix is meaning... I think... is that when replying, you have the choice to reply as (in my case):

Logged in user: southerndave [other].

Now if I want to reply to you using my other journal account I'd click on the [other] and type in my other username and password. So if this reply shows up as posted by "newissues" and has a chocolate fish stamp for an icon, this is how it works. I think.

Never mind, it should make much more sense in the morning and after a couple of Disprin...

[i]goes off to find out what newissues' password actually is, because he's forgotten it...[/i]