It's out, so i tried it: KDE 4.0. It made huge progress since i last tried it about 8 weeks ago. I can, for example, now use two displays at different resolutions, and still get the Desktop right for both (i need to set them up manually in my .xsession, since the kde RandR applet cannot do that, but that's no problem).
However, as long as basic functionality like "moving and resizing the task bar" is not possible at all, i don't care about the excuses that the developers find for releasing this hunk of code, i'll just go back to 3.5 and use some selected KDE4 apps (konsole4 really rocks) on my machine.
See you later at 4.2.