There are some issues with this and some have actually installed the windows app ‘winrar’ under wine to make it work. However, if you have kde3 installed also, which many do - so long as you have all the archive packages installed (rar, zip, etc…) You can use the kde3 file manager and use right click extract here.
If you have kde4.1 factory repo’s, there is aKu - it works on rar files.
It is so surprising things get fixed so slowly. This is a rather major bug to me (no more extracting). I wonder when KDE4.x will be really ok, I hope that ‘x’ will not be too high. It for sure is NOT ‘0’ nor ‘1’