Is there a

[Intense Fury]

Is there a code where you can ban observers

[Sauron]

yep theres a code for observer banning! Try a search here in the sam forum there should be somewhere the exact code

[Goober]

you can also just set a password for observers
right before you start the game, pull down the console and type this in.
/net_strobserverpassword="anythinghere"

That will keep them out unless they know the password.
PS....substitute anything you want between the ""

[Intense Fury]

ok thanx goober