... Canon hasn't released an updated 200/1.8 while Nikon released a spectacular lens in the same class. But I see no reason to retract my statement. I was told there was a replacement - what happened to it is anybody's guess.
We can only wait and see what actually happens this year: one side of me favors offering high end f/2 telephoto primes at up to the longest focal length at which this is economically viable. (And Nikon once had a 300/2: [a href=\"http://www.cameraquest.com/nf3002.htm)]http://www.cameraquest.com/nf3002.htm)[/url] This is based on a guess that about f/2 is the fastest that a long telephoto lens can be with acceptable control of aberrations and such, and the idea that extra lens speed allows the use of higher sensor resolution (roughly, smaller photo-sites) under a given combination of lighting speed needs, giving more telephoto reach with a given focal length. Even if that sometimes involves significant cropping, or changing to a smaller format body for long telephoto work.
The only signs of such pushing at telephoto lens speed limits lately are the lens speed Nikon 200/2 and Olympus 150/2, and maybe one could count the recent fast zooms from Olympus, 35-100/2 and 90-250/2.8.
In one sense, the Nikon 200/2 is not in the same class as the as the Canon 200/1.8 when used on current Canon high end bodies, as the Nikon can be used with higher resolution sensors: 5.5 microns compared to 7.2 to 8.2 microns. The high end Nikon lens-body combinations give higher angular resolution of subject detail, comparable to about 260mm on a 1DsMkII or 300mm on a 5D or 1DMkII. That puts Nikon's offering in a different market position for now, more like that of a Canon 300/2.8, which is I believe a far better seller than the Canon 200/1.8 was.
This changes if a 200mm is used with the new 400D, but a real increase in demand for a Canon 200mm faster than f/2.8 will probably not occur unless and until Canon offers a high end model with pixel spacing comparable to 5.5 microns. Maybe something like a 16MP model in the "1D" format, to replace the 1DMkII?