Re: Trapezoid-Acceleration on which cards?
For the record, the 256 driver release series supports trapezoid acceleration by default, without having to enable the AccelerateTrapezoids NV-Control attribute.
Since I don't know if it's been mentioned anywhere before, it also supports accelerating all types of RENDER gradients.
Gradient acceleration works on all Geforce 8 series products and newer while trapezoid acceleration is only supported by anything higher than GT200 as Aaron pointed out.
If you have any numbers of how that impacts your Java2D back-end or other things, I'd be interested to see a before/after comparison or against other drivers.