Canon has the sensor size/density and the processor. Sony has the sensor size/density. Nikon have the body and the OS.

Final image quality comparisons still need to be made to see what the end result is, but the above, except for the new Sony splash, seems to be the recurring story for the past few years.

Personally, I couldn't stand to use any of the existing Canon bodies full time. They all feel cheap compared to the Nikons and feature a real lack of ergonomic thought.

I do think Canon are going to clean house with the new 5D though. Sony should also do very well with its new lineup if the image quality is good. If it's up there with Nikon's image quality, it's made an incredible offering at that price point.