If you have a separate /boot partition (in part to deal with
the BIOS limited range of boot sectors), and you upgrade
to RedHat 5.2 from RedHat 5.1, then the installed will
create the vmlinux and System.map symlinks in the /boot
directory after unmounting the /boot partition, rather
than in the /boot partition file.
The installer does not twiddle with things like that. The partitions
are mounted before installing RPMS and are not unmounted until reboot.