Canon's EOS 1Ds launched with best-in-class resolution, and the 1Ds Mark II keeps it there. The recent revision adds support for Canon's new WT-1 802.11g wireless transmitter and an orientation sensor, and continues to provide very low noise, instant start-up, and full 35mm sensor.
The EOS-1Ds, at $8,000 continues its premium over Nikon's top of the line D2X and Canon's recent EOS 5D. The premium gets top-of-the-line resolution and a professional body. The D2X also has a pro body, and supports GPS receivers, but has lower overall resolution.