Description of problem:
After using preupgrade to upgrade a number of machines, we notice that the whole process of upgrading involves running preupgrade and then after it finishes running 'yum update' which again updates about 3/4 of the packages already updated by preupgrade.  There needs to be an option so that preupgrade could just load the very latest updates while it's doing the upgrade instead of requiring the user to update each package multiple times.  This sure would cut down on the total time necessary to upgrade these machines.