I have no idea what package caused this, but since running yum upgrade yesterday, Sun Java is no longer installed.
You uninstalled it again.
This is a known bug but it's a bug in the Sun RPM, not in java-1.4.2-gcj-compat. On Fedora it's best to just use java-1.4.2-gcj-compat. If you must install Sun's Java then try the Sun Java RPMs from jpackage.org.
This is already mentioned in the release notes and expanded currently for FC5. Refer to http://fedoraproject.org/wiki/Docs/Beats/PackageNotesJava for the details