With gdm-2.19.5-3.fc8, gdm writes errors to /var/log/secure about not being able to load /lib/security/pam_gnome_keyring.so. /etc/pam.d/gdm mentions pam_keyring.so but that file is not present. The file seems to be provided by gnome-keyring-pam package. Installing that package fixes the problem. The gdm package does not depend on the file or the gnome-keyring-pam package that provides it.
Matthias fixed this last night I believe.