Professional digital photographers shoot Nikon out of necessity. Whether it's a Nikon D1 or the Kodak 760, F-mount Nikkors are what will be attached. Kodak hasn't made an EF-mount camera in over three years, and Canon's D30 competes with the Fujifilm FinePix S1 Pro at the prosumer level. It was only a matter of time before Canon released a professional body, and has done so with much aplomb.
The Canon EOS-1D is environmentally sealed like the Nikon D1 and the Kodak DCS 760. Rather than use a CMOS imaging chip like they did in the D30, Canon has gone with a 4MP CCD for the imaging sensor, but has a CMOS sensor for its 45-point auto-focus system bringing it into line with its film cameras. The EOS-1D matches the D1's 1/16,000 second minimum shutter speed and ISO sensitivities from 200 to 1600 (in 1/3 steps). Like the Kodak DCS 760, the Canon EOS-1D's CCD is slightly larger than the Nikon D1, resulting in a 1.3x crop factor over 35mm film. The EOS-1D supports compact flash and the IBM microdrive-like drives, and offers the shooter to record both a JPEG and a native-raw file at the same time which is useful if you want the expediency of JPEG shooting with the benefits (or safety net) of having the raw file without having thoughts of file formats distract you from composition and timing.
The EOS-D1 lacks a serial port to connect to a GPS receiver, which both the Kodak DCS 760 and Nikon D1 series have. The EOS-1D has slightly lower overall resolution compared to the 6MP sensor in the Nikon D1X, but has the ability to fire up to 16 raw exposures at up to 8 frames per second (a slower 3fps setting is also available). The EOS-1D has impressive noise control, a stop better than the Nikon D1X, but reviews have indicated visible banding patterns on dark scenes at high ISOs which may be problematic depending on the subject.