Red Hat is planning on upgrading Bugzilla to BZ5 in September. There's a test instance running now at http://bugzilla5.redhat.com/

Since Fedora is a major user and stakeholder here, it'd be helpful if we make sure everything works for us. If you find any bugs, report at https://bugzilla.redhat.com/enter_bug.cgi?product=Bugzilla&version=5.0