It seems to me that if the B7 comes out as a 2005.5 car, buyers would be nuts to purchase it until the 2006 model is sold. The 2005.5 models will have 1/2 year before they will be depreciated as a year old model.
I have always hated Audis .5 models. Why don't they put all changes in at model year change, rather than in the middle of the year. The early buyers think they have been screwed.
Audi has never done a .5 model year change as extensive as this one, with the sheet metal front and back changes. It is my belief that Audi will make it a 2006 model.

The A3 coming out in May will be a 2006, but that is only because it is a brand new car.
The A4 is coming out next month because of the new 3 series coming out in Spetember.

Another thing as well, is that the new model years are coming out now in Europe and the B6 stopped production 2 months ago. It would be too much money for Audi to keep on building the B6 just for the U.S market.
You would be surprised how many people have passed on the B6 to wait for the B7!!