Even though there has been many problems with the Zen technology used in Kendwood CD-ROM drives, it is one of the first steps towards higher speed cd-roms. And based on the method in which it works - by difracting a laser into 7 beams and then reading it in parralel, if improved this method could work very well in producing higher read speeds without increasing the rotation of the cd.
Kenwood has their problems, but should be given some recognition for the fact that they are really the only company taking any steps to improve cd-rom speed at the moment. Look at Creative, their 52x cd-rom sounds like a frickin jet engine, and compare it to the 72x Kenwood (which I have), which you can barely even tell that the cd-rom drive is reading it's so quiet.