The behavior of up2date does not match the documentation in the manual. The documentation in the manual says that you don't need to touch the version number pulldown menu, that it'll default to Red Hat Linux 6.1. Unfortunately, that is not true. It defaults to "6.1", which does not correspond to anything in the priority.redhat.com site. The program will not correctly find updates until you use the pulldown menu to explicitly select Red Hat Linux 6.1. Either priority.redhat.com needs a symlink so up2date can find the correct version even with the incorrect default, or up2date needs to be fixed to match the manual.
Fixed on the priority servers.