I did an locate and found it here:
/usr/lib/perl5/site_perl/5.6.1/Mail/SpamAssassin.pm
I've installed SA using RPM btw.
That's not so good, seeing as your current perl is 5.8.x and has paths matching...
Perhaps a re-install will help, but I'd recommend using SRPMs or tarballs instead of prebuilt RPMs unless you're using the *exact* OS and release Theo builds them for.
