and it has to answer somehow to Nikon's upcoming D4 this year...
This is exactly right: remember, this is a business, not a hobby for Canon and Nikon. Nikon may have gained some market share, but Canon must be gorging itself on profits from the 5D2. Now everyone knows that video is the "killer app" for pro DSLR's, and they're using the Great Recession to re-tool for that. There aren't a lot of people who will lay down $10k for a high-end FF still camera, but there are a lot more who will lay down $10K for a high-end FF still+video camera. I speculate (!) that part of the delay in some of the lenses is to rework them for video, and for other planned or possible changes in technology (>FF?) Nikon is likely doing the same. Since the 5D2 continues to sell quite well at nearly the original price (after how many years?) no one in the pro DSLR market is going to ignore video at this point. (Note to DSLR still-camera purists: you are now officially old fogies)
My guess is that Canon has several versions of prototypes for each of its pro bodies out in circulation, and they're just waiting for Nikon to commit to its answer to the 5D2 and 1D4. For those who claim the 1Ds-series is the prestige camera, I repeat that it's all about money, not prestige. If you want to know when the 5D3 or 1Ds4 or 1D5 will hit the market, I suggest you start following the NikonRumors web site.
