[quote=CrimsonWarrior55]
The thing is, you as the writer know EXACTLY what these secondaries are thinking. So writing them as if you don't is impossible. And can also lead to a horrible case of talking to yourself when your characters need to interact when you're not careful. 
[/quote]

Let me get this straight. You are flat out stating that this is impossible when I already brought forth a couple of examples, both of which are major works (One of which is now an HBO television series of remarkable renown)? No, as the writer, you have the advantage of using a number of narrative styles and developing your own unique narrative voice.

You really should check out this article which describes several other "impossible" narrative modes. Writing in first and second person is a rather interesting exercise and presents their own challenges. The differences in third person are somewhat subtle.

http://en.wikipedia.org/wiki/Narrative_mode