Exactly. If your HDTV does a good job of upconverting it's likely you won't notice any difference (or you may even notice a negative difference) if and when PS3 upconverting occurs.
Have you guys ever watched a well encoded DVD upconverted on a good upconverting player?
I first got a Denon upconverting player almost 4 years ago, and was blown away by the quality. At the time, it third only to OTA HDTV broadcasts followed by cable/satellite HD for PQ. I've since replaced it with a player that upconverts even better, and also play high def DVD's from that "other" high def format.
OK, my HDTV is only 1080i, it's 3 years old, and it's only a Sony. But all it does is enlarge the image to fill the screen. There's just no comparison to a good quality upconverting player. :