I took the plunge and installed KDE 4 RC1 on my Gentoo installation. It went quite smoothly with the only thing not working being the networking stuff. Once again, Kopete caused problems so I skipped the whole thing. Maybe I’ll see if I can get that fixed this morning.
So far I think it’s looking pretty good. I’m not sure if this is supposed to happen or not, but it looks like the KDE 3.5 and Kicker are being loaded just before the KDE4 stuff. That makes me confused.