Most Gecko-based browsers on linux do actually scan /usr/lib/mozilla/plugins at startup, so you might find something like:
ln -s -f /usr/java/j2re1.4.2_05/plugin/i386/ns610-gcc32/libjavaplugin_oji.so /usr/lib/mozilla/plugins/libjavaplugin_oji.so
might be good enough to cover at least Gecko browsers (and let's face it, Gecko is the best rendering engine out there
). Of course, it would be nice if Sun's Linux RPM would actually put at least that soft-link in - c'mon Sun, get it done!