This is something I've been curious about as well. From my understanding, there are (3) situations that can potentially cause you to fail. 1) Failing visually 2) A check engine light or code 3) The O2's being "not ready".
Is this accurate? I'm not too worried about 1 or 2, but #3 is the one that you can't really be aware of until you fail. I've read that it can be addressed in a tune, but I don't know what the tuners have included. My tune has the rear O2's turned off since I'm not running cats, but from my understanding, by turning them off, they can still trigger a "not ready" status during inspection and fail. Let me know what you know on the subject. I have until June '13, so it's not urgent.