Long a rumor, now it's real. Nikon released the D3x, a 24 MP monster in a D3 body. There are some very nice sample images here and some other ones in a annoying and crappy flash interface here - gorgeous images though. Gorgeous detail and beautiful color. However, the price of $8k! makes it completely irrelevant for me. If you're a commercial studio photographer then of course this is great, but perhaps offers not that much different from medium format digital except for the use of all your nikon lenses. If you're a landscape photographer, you have to be super rich or super successful to afford this and then you'll still get far better quality using large format analog which will set you back far less. Or go for the Canon 5D mk II, which offers basically the same quality (for landscapes) in a much smaller package. Let's hope Nikon comes out with a D700x to compete with that using the same sensor as in the D3X. The D3x is a monster. A beautiful one, but a monster nevertheless.
Update: Ken Rockwell writes "... Nikon dared ask $8,000 for a $5,500 camera that is the same thing as the $4,200 D3.", and "The D3X is Nikon's greatest camera ever; it's just not worth $8,000, except to turkeys." He is absolutely right. Don't bite at this price. You can get the same quality using Velvia 50 in any old 35 mm Nikon you can get for $50 on craigslist if you own a good scanner or use a good scanning service.
Update II. Wonderful analysis by Thom Hogan here.