higher spin speeds and the insertion of a "white" color segment (which is obviously used to make the color white instead of having to solely rely on the combination of blue, red and green to make white) have all led to a reduction in the rainbow effect.

I notice is occasionally on my DLP projector, but less now than I did when I first bought it. The LED DLP seems almost like a perfect technology, by the way - small form factor, big size, no bulb burn outs...