Ok, this is mostly in regards to the megapixel war and how increasing resolution leads to higher pixel density, smaller pixels, less light capturing ability per pixel, and ultimately noise. Yes, this is still true.
HOWEVER... the resolution of the 7D at 18 seems so high that it pretty much doesn't even matter for most regular uses (i.e. not printing super large images). We know noise is at a pixel level. The noise on high-resolution sensors such as the 7D is largely irrelevant for most uses, as the resolution seems high enough that we're nowhere near viewing at 100% anymore to even see the pixels.
I don't know if I'm getting my thoughts across well. Let's put it this way - even if the noise were identical between a 7D (18 mp) vs a 40D (10mp) (although I'd say it's slightly better on the 7D), that's at 100%, pixel peeping. When viewing two images taken similarly, the noise on the 7D can appear less BECAUSE of the higher resolution. I think it's approaching a point were perceived noise at non-100% is improving once you hit a certain high-MP - an that we're getting there with 20mp or so.
Ok, so we still have an issue when it comes to cropping, but well, you can't win 'em all. That said, any image that needs to be cropped that was taken on a lwer res senor probably won't fare that well detail wise.
I just think maybe Canon did a good thing going to higher resolution with the 7D in this regard.