Nikon's flagship full-frame DSLR, the D3, is a lot of things, but a megapixel warrior it is not, shooting a mere 12.1MP to other flagship DSLRs' 20+. Nikon said it was avoiding the pointless megapixel war. But the latest firmware update for the D3 turns up a string for the "D3x" containing the image sizes "6048x4032 24.4 M" and "5056x4032 20.4 M." Given that everyone else is speeding along pro DSLRs with 20+ megapixels, the D3x probably exists, and shares common code w/ the D3. Nikon expert Thom Hogan goes further, suggesting the reason it's in the code is because "there are some D3 bodies out there with the new sensor being tested."
