Little interesting bit I noticed in practice is that vertical elements toward the inside of the rear wing have taken on a new form. They both lean in the same direction on Takuma Sato's car making for an assymmetrical rear wing. Davidson's car had the more conventional symmetrical rear wing. Didn't see any pictures of Button's car with enough resolution.
Also, Williams seems to have copied theis feature--the vertical elements, not the assymmetry--with obvious vertical elements. They don't seem as sculpted as on the BAR but they are there nonetheless.
Pretty quick copying.