There has been an intrusion in one of the fedora servers that was used for key signing of the apps. The extent of the damage is being analysed. Till then fedora users are requested to hold updates and also update GPG keys as when update is made available.
Full Story :- *www.redhat.com/archives/fedora-announce-list/2008-August/msg00012.html
Full Story :- *www.redhat.com/archives/fedora-announce-list/2008-August/msg00012.html