In RedHat 6.0, it appears that the kernel packages no longer include st as a module but instead have st compiled into the kernel. However, /etc/rc.d/rc.sysinit still runs modprobe st if /proc/devices indicates the presence of st and USEMODULES is true. This is harmless, but does result in an extra error message at boot time. I don't know whether it would be better to throw away the error message or to try to determine whether st is a module or not.
in the latest initscripts in Raw Hide, it won't try to load the module if it's compiled in into the kernel. We might also start shipping it as a module again anyways...