I'm an old guy who shot film. And on that basis have never been overly obsessed with how clean an image is regarding noise, simply because grain of some sort was always present, and photo's that were good enough then are still good enough now. The sensor of a 5d does not obliterate photographic history just because images are now 'clean' (and some may say, myself included) sterile. In any case, I see more 'improvement' in using good lenses rather than more pixels.
The whole concept of choosing a film because of the grain (noise) characteristics seems to have proverbially left the building, and I don't see anything replacing what was a key ingredient of self expression in any alternative's offered by 'pixel peepers'. It is clean or nothing. Which makes me wonder, do they throw away and delete their older noisier images, or always have to explain them away by saying 'of course my camera wasn't as good in those days'?
Photography and self expression is going to hell in a handcart if the spec of a Canon or Nikon dictates what is suitable as a top quality image.
Steve
P.S. I should have declared my interest in the G1, which I hope to be adding to my kit soon. The idea of a set of excellent lenses (especially when Olympus release their offerings) that can be interchanged between bodies offering different characteristics is the true revolution on offer here, not the pixel count. It gets back to the idea of choosing tools as a means of self expression around a common element, much as your Tri-X could have been loaded into a Sinar, Nikon F, a Leica M3, or an Olympus Pen. And other photographers somehow recognised that you made these choices on purpose, not as a response to needing the latest camera. Perhaps it will help photographers grow up, and once again embrace the democracy of photography, where a grainless Stephen Shore can exist on the same wall as a grainy Bresson.