With suitable care in capture, post processing and printing, you can make an exhibition-quality 24x36 from 12mp. I've had someone actually take a magnifying glass to one of mine. There was a mild complaint about a little stair-stepping on one high contrast line (about a half inch long - remember this is on a 24x36" print), but that was about it. Seriously, the detail on this one is really good. Of course, conditions were near perfect: 1/100th, f/8, 24-70/f2.8 @ 35mm, big sturdy tripod, cable release, mirror up, absolutely no wind, and details everywhere in the frame. Come to think of it that one was shot on a D2x, not the D3, but still the same 12mp.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!