All,
We are currently testing the yum-utils and yum-utils-plugins in the dev.centos.org repository.
The two main plugins that this allows that I think would be great for normal users are protectbase and fastestmirror.
See the announcement on the centos-devel list for details:
http://lists.centos.org/pipermail/centos-devel/2005-November/000947.html
Thanks, Johnny Hughes