Thanks Rex. In the mean time a workaround to get the result needed was at my side:
1) yum remove phonon-backend-xine 2) yum groupupdate kde-desktop
keeping track of delta between packages removed in 1) and not installed in 2) I get:
package k9copy is not installed package kdeedu-kstars is not installed package kdeedu is not installed package kdeedu-math is not installed package kdeedu-libs is not installed
yum install k9copy kdeedu-kstars kdeedu kdeedu-math kdeedu-libs
ok!
I'm going to test this finally release 4.2. Gianluca