I have tried both qt-3.0.4 and qt-3.0.4.1 ebuilds, both cause major slowdowns on gentoo-ppc. Basically when launching any qt based application you can wait (depending on your machine speed) from 30 seconds to 2 minutes for initial application launch. After that they perform perfectly, but seems to take forever to initialize. Makes kde3 mostly unusable. Reverting back to the last qt-3.0.3 ebuild restores proper speed, apps launch immediately.
This also seems to cause problems trying to compile newest KDE, users have reported that artsd complains about not being able to install qt (didn't happen with me), but it seems that the ebuild is trying to specifially pull qt-3.0.4.1
This has been fixed by the (still masked for testing) qt-3.0.4.20020606.ebuild from a recent cvs snapshot