I have heard that it is all gearing up for wide availability of Fermi in March.
Instead of doing an Ati and releasing the product early with insufficient drivers and poor availability (HD 58xx series cards did not come out in the UK until December/Last Week of November at the earliest and HD5970 cards are still not released here) nVidia will be releasing on mass in March with relatively mature drivers too (well I do say relatively, obviously there would still be the odd gremlin or two that you get with a new card for the first couple of months).
John