Perl modules managed by RPM should be installed into vendor_perl, not site_perl. Almost all modules have been updated to correct this; as of perl-Cyrus-2.2.10-11.4.fc4.i386.rpm, this is one of two in the development tree that doesn't seem to be fixed yet.
Oh, no, wait -- 3. ImageMagick does it too. :)
Cyrus is not in Fedora Core anymore. I have a version for Extras prepared that fixes this issue (among others). I just can't seem to persuade the build system to obey... I'll close the bug when i manage to build it.
So, uh, presumably this is good now, right?