DPR has just posted their review of the 1D Mark IV.
The Final Word (From DPR)
A lot has already been said about the 1D Mark IV, both by people who have tested it and those who have tried to weigh it up against the D3S and that kind of nit-picking makes it easy to overlook what an astonishing camera it is. And looked at from a neutral perspective, both it and the Nikon are unmistakably the best sports cameras that modern technology allows.
Its talents are slightly different to those of D3S but its strengths will be a great asset to many people – the smaller sensor that prevents it competing at the very highest ISOs delivers the kind of extra reach that many touchline shooters will appreciate. Frankly there's more to both cameras than just their high ISO performance and, while the Mark IV isn't the best high ISO camera on the market, it's still an exceptionally good one. From the point-of-view of the tasks it was built to tackle, there is nothing that can touch the detailed, high resolution images that it can deliver ten times a second.