Thanks for the keybinder hint. Running kupfer master with keybinder v0.0.9 renders a functional kupfer on my Scientific Linux 6.1 box.
I had focus problems when using compiz and a keyboard-shortcut to kupfer, which are gone when using keybinder.
It does render a little bit weird; the window is missing (or has no opacity). But I'll check to see if there's a different report about that.