Yeah, some here are missing the point. Some (apparently not all) 5D2's exhibit offensive noise patterns in shadows, particularly at low ISOs. Whether you push the blacks or not, the offensive pattern is there. This has sidestepped into the purely subjective discussion about how much post processing you should do, etc, etc, where some people are trying to assert some kind of superiority over others by claiming only they know how to expose properly so that you wouldn't even want to push the shadows, etc. All that trollish discussion completely misses the point, as does the guy with the 5D2 that doesn't (apparently) have this problem. For plenty of people - enough to have this issue come up time and time again on this and other forums, the problem exists.
Canon is almost certainly going to do nothing about this problem since it doesn't get a lot of press. Looking at DPReview's review of the 5D Mark II for example shows no such problem, but their photographic noise tests don't show the noise in any real shadow areas. Their dynamic range tests only show corrections trying to restore highlight detail and don't bother to show pushing DR out of the shadows. The Digital Picture doesn't appear to have even bothered to look at the noise under ISO 400, etc, etc. It's probably just something that those of us with 5DII's that are affected will either have to live with or sell the camera and get something else.
-K