Very little works stably thus far in KDE4. I'd really recommend that you 
don't start using it just yet =). If you absolutely insist, there are some 
rough and ready instructions that mostly work here: 
http://mail.kde.org/pipermail/panel-devel/2005-July/000354.html

Using the qt-copy in KDE's svn is working fine for me.

Regards,

Jes Hall
 
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