1.5x isn't bad: the Canon D60 is 1.6x and the Sigma SD9 (with the Foveon sensor) is 1.7x. There are only a few cameras that are better, and they're expensive: the Kodak DCS 760 is 1.3x and the Contax N Digital will be full frame.
And I wouldn't dismiss CCD technology yet: the D100 will have twice the resolution of the Foveon sensor in terms of the number of pixels in the final image, so in pure luminance terms it will be able to resolve finer detail. There's also the question of how much noise will be present: traditionally CMOS sensors perform worse than CCDs in this respect.
I guess we'll just have have to wait for samples from the D100 and Sigma SD9 to see where the trade-off between resolution and colour accuracy occurs.