After extensive testing on the CentOS-devel list, Tru Huynh has added yum 2.4 (and all its dependencies) for CentOS 3 to the CentOS Plus repository for CentOS 3. yum 2.4 has numerous improvements over 2.0, and the accompanying yum plugins (fastestmirror, priorities, etc.) add useful functionality. A backported version of the yum C metadata parser was added as well. This makes the metadata parsing phase much faster. Instructions for installing yum 2.4 can be found in Tru's mail to the CentOS-announce list.