smaller pixels yields lower pixel pitch, so yeah, an 18 mpx camera with that sensor size would be crazy.
when i see canon making efforts to get around that pixel pitch (full frame, bigger pixels) i am impressed.
and as far as new models go, the mk 3 is NICE. and look at the 5d, the best comprable camera nikon has is really the d2xs, for tons more money. at that price range there is nothing from nikon. so i bought the d200 . . . not that i'm unhappy with it, i'm not. but jeez, with moves like that and smaller sensor sizes with lenses built for that format whats going to happen if 20-30 mpx's becomes a industry standard? there is NO way they will get it in that sized sensor.
while megapixels aren't everything . . . people won't stick with nikon for making poor desicions. and whats the word on who's making their new sensors? sony is done with them right? ? when there are things they could do to improve, and havn't changed it makes me wonder if they will continue on that path, while canon will continue to do something about it.