the red hat solution to have an up2date red hat repository is to use the red hat satellite server. it's not cheap.
now, if you're talking pre-enterprise versions of red hat (i.e. rh up to 9) it's a silly waste to go that ^^ route, and you could just rsync to maintain a local mirror from http://www.fedoralegacy.org/download...cy-mirrors.php
if you're talking enterprise versions of red hat (i.e. rhel up to 4) and an automated solution, you have the rhn satellite route and the red hat rhn route since red hat updates are not offered for free. yes, each machine needs to download its own updates in the latter case, but since the updating can happen automatically, at least it's no work.
the other way to go is to manually download from rhn.redhat and maintain your own fileserver and then install updates manually (of course, it is only ethical to use these downloaded files for as many systems have paid for rhn network access), i.e. rpm -uvh http://your-domain.com/rh4/rpm_to_update-4.0.1.rpm
if using some apache goodness, or mounting by nfs and then just pointing it at the nfs mounted folder. you might be able to configure all of these rpms as an up2date repository, but i can't say i know how. either way, this manual downloading would be lots of work, but sticking totally with red hat (as in not fedora or centos or scientific or whatever), these are the only methods i can think of.