Dude.... THE EGG IS BACK! I love it.
Anyway - as said, this is a public message board, ANYONE can read along without you knowing. Some people (on other boards I visit, mostly) seem to have no grasp of the concept at all that people are rteading everything they post, and that these people may not necessarily post something themselves. I saw someone here say that it's not so bad since we're all a big happy family here and know each other but that doesn't take into account all the lurkers that visit the boards - people who only read and don't post. So unless your board is password-protected, you should consider anything you write as open to anyone on the world with an internet connection.
That doesn't bother me though, I keep it in mind when I write here, and only post things that I am comfortable sharing. So in that sense I don't mind people reading over my shoulder either, although it can be annoying when you're trying to concentrate on a difficult matter in a serious debate or somesuch.