As KR says, the 5D is the sharpest DSLR at 100% crop. I'm a Nikon user, but if I ever move to full frame, Nikon has some serious catching up to do before they could sway me away from 5D and its successors, despite Canon's comparatively lousy ergonomics.
That said, I'd like to see a 100% crop of an image from the D3x as well.
I know we shouldn't be jerking around too much about sharpness, but, just for interest's sake, here's a 100% crop from the 5D MkII compared to one from my D40, taken with my sharp prime lens stopped down:
5D MkII (first image from that list)
D40 (a similar portrait type of subject), ISO 400, 50/1.8 Series E stopped down to f/2.8
Yes, my photo was manually focused and at ISO 400, so any lack of sharpness could very well be my own fault.
Still, I think the megapixel race is starting to matter again when we're talking about the difference between 6mp and 25mp, and also overall sharpness.
Oh, yeah, and those are some great shots, Keith! You must have quite a talent to be able to grab all the sharpness from that camera.