Doubtfull that current A3/A4 will have B&O audio optional,
as f.e. A4 is about to be replaced by the new model.
Considering that the new Audi A5 is the first model from the platform of the new A4,
(it basically is the coupé of the new A4),
it would seem logical that the new A4 can be ordered with B&O audio,
probably not the Advanced Sound System, but the Premium Sound System.
The Audi A5 and R8 can be equipped with the Premium Sound System (A5 € 895,-, R8 € 1440,-),
The Audi A8 and Q7 (autumn 2007) can be equipped with the Advanced Sound System.
More details will be added shortly.