An installed library that has no installed packages depending on it is referred to as orphaned. One of the tools used to determine which libraries are orphaned on a Debian system is named deborphan. What is the Fedora equivalent?
It appears that package-cleanup can perform a similar task with the following command:
$ package-cleanup --leaves
or, to include more than just libraries
$ package-cleanup --leaves --all
package-cleanup is in yum-utils package, which is available for installation via the Fedora repositories.