The libsamplerate RPM (both the lib and the devel RPM) in the FC5 repository is still a FC4 RPM. Check http://fedoraproject.org/extras/5/i386/repodata/repoview/libsamplerate-0-0.1.2-3.fc4.html for the RPM itself.
Taking over as maintainer since Anvil has other priorities This is normal, in Fedora Extras the repo contains the last and the previous version, the one you are mentioning is the previous one. Yum will automaticly select the newest one for you. Either way this .fc4 one is going away since I'm pushing a new version todo.