The preferences dialog in 2.0.2 only lists upnpplugin and scanfolderplugin thought it did install all of the plugins.

run kbuildsycoca and restart KT

Yeah, i already figured out that much, but still:

• "kbuildsycoca" didn't help
• "kbuildsycoca --checkstamps" didn't help
• running "kbuildsycoca --global" as root didn't help
• restarting ktorrent didn't help
• restarting kde/xorg didn't help
• restarting my computer didn't help
• re-installing ktorrent didn't help

As 2.0.2 is not in Gentoo's portage, I just cloned the 2.0.1 Gentoo ebuild to use for 2.0.2.

I've got exactly the same problem in Mandriva x86_64, since 2.0beta. Tried the same things as J.
Version 1.x worked fine. I built rpm's for it; then with version 2.0beta1 until now: no plugins.
In Gentoo it also works fine (version 2.0.2 is in portage today).

They are probably installed in the wrong path.

Wait a second, this problem sounds familiar, I believe there is another thread on the forum about this.

OK I have found the thread :

http://ktorrent.org/forum/viewtopic.php?t=756

It seems make install installs at the wrong location for Mandriva 2006.

You need to copy the following files from /usr/lib/kde3 to /usr/lib64/kde3 :
ktinfowidgetplugin.la
ktipfilterplugin.so
ktpartfileimportplugin.la
ktscanfolderplugin.so
ktsearchplugin.la
ktupnpplugin.so
ktinfowidgetplugin.so
ktlogviewerplugin.la
ktpartfileimportplugin.so
ktschedulerplugin.la
ktsearchplugin.so
ktipfilterplugin.la
ktlogviewerplugin.so
ktscanfolderplugin.la
ktschedulerplugin.so
ktupnpplugin.la

Then run kbuildsycoca and restart KT.

Strangely enough, after re-emerging ktorrent one more time (now from the official but basically identical ebuild) fixed this.