This might seem like an old topic, but the recent wave of 8MP cameras in a wide variety of sizes makes me curious again. I have seen arguments that 8MP about matches the resolution of good ISO 100 35mm films like Provia, and if that parity holds, it might be interesting to compare sensitivity, meaning exposure index capability.
So, to all users of the 1DMkII, 20D, or any of those 8MP 2/3" format digicams, how high do you find that you can go with the ISO setting and still have noise that is no more visible or objectionable than the grain of a good ISO 100 film?
P. S. To my mind, the answer to this question indicates something like the true "ISO speed" of the camera; any higher, noiser setting is definitely akin to push processing.