Indeed! Whilst I understood the rationale for QE2 to wear white to accommodate all the different coloured sashes, Camilla is not constrained by the sashes as she only has the Garter as her "senior" sash and can wear gowns and jewellery to match the Garter sash.
As the UK did not offer orders to spouses to visiting heads of state, I am not sure Camilla will be receiving all the overseas orders herself.
Camilla certainly looks like a queen but I've seen her look even more regal at previous state banquets. Maybe it's the blue dress rather than white that takes it down a notch.