Nikon has lately been quite aggressive with its DSLR line, determined to hold on to its current market share I presume. Given that the imaging business is now the main revenue earner for Nikon, this is hardly surprising. I think that no one expected Nikon to completely revamp the imaging sensor in a point upgrade to the D3. A new FX sensor within 2 years of the old one, kudos to Nikon!
It is uncanny how Nikon and Canon appear to produce cameras with the same feature within a few weeks of each other. The Nikon D90 had HD video, and soon after the Canon 5DII came out with HD video. The same pattern has been repeated with the latest announcements - Nikon comes out with 102400 ISO, and Canon follows suit a week later.
Looking at the specifications, it seems that Canon has targeted sports photographers, sacrificing the FF sensor to keep to the 1.3x format. This along with the higher resolution should allow sports photographers greater reach and ability to crop.
The Nikon D3s, on the other hand, seems more targeted towards news photographers, although also thrown in is the 1.2x crop mode as a convenience to sports photographers. Thanks to the upgraded imaging sensor, the D3s is able to compete with the 1D Mark IV, despite being a two year old model.
Only time will tell which of these design choices is a winner.
Canon has an obvious advantage when it comes to the video implementation, due to its long experience with professional and amateur video cameras. But quite apart from this, a bias may be evident in how the video has been executed. The Canon appears to be targeting Videographers, whereas the Nikon is targeting primarily still photographers who want to take advantage of the occasional video.
These are just speculations on my part; it is unlikely that we will ever get to know the real reason for Canon sticking with the 1.3x format sensor, or for Nikon avoiding the 1080p HD video format. If I were to hazard a guess, I would say that Canon believes 1.3x format is better for sports photographers, and had not anticipated the upgraded D3s. A 1D Mark IV with support for 102400 ISO and HD video, compared with the original D3, would have been a clear winner.
The introduction of D3s just before the announcement of the 1D Mark IV has despoiled Canon of a clear victory here. But Nikon's choice of 720p format video is puzzling. My guess is that the Expeed chip isn't fast enough, and that we will not see 1080p HD video until the next generation Expeed chip comes along.
The best thing with these two cameras is that each has its strengths, and there is no clear winner. Therefore photographers using either brand can get on with the job of taking more photographs, rather than agonizing over the superior features of the competitive brand.
Nikon would hit a home run if they introduced an upgrade to the D700 with the same sensor as in D3s. I for one would buy such a camera immediately. The D3s is too serious a camera for an amateur like me, therefore I could never justify buying one.