One of MTV's writers, Scott Aukerman, posted on their blog that the Bruno/Eminen/Ass in face business was in fact planned.
"Yes, the Bruno/Eminem incident was staged. That's all anyone wants to talk
about, so let's get it out of the way. They rehearsed it at dress and yes, it
went as far as it did on the live show then."
Well then, now that's settled.