I just have the same problem: "none" of my usb sticks will
mount
automatically on Fedora 9, but they will on fedora 7 and 8!
I found a solution (at least for two sticks):
yum update
yum --enablerepo=updates-testing update dbus e2fsprogs
reboot
or just wait until dbus and e2fsprogs make there way to the default updates.