When managing alot of systems (virtual or physical) it makes sense to centralize the package management. It also saves you alot of time.
Spacewalk does exactly that for RPM-based systems like CentOS, Fedora or SLE. Its the community and open-source version of the RedHat Network Satellite Products (RHN). It brings you alot of nice features like
- Systems inventory with hardware and software info (DMI)
- Centralized package management. Installing / Updating software on systems (single/grouped/batch)
- Errata overview for systems (security/bugfixes/enhancements)
- Kickstart / Provision systems
- basic config file distribution (better do this with puppet/chef)
- basic monitoring (better do this with munin/graphite/ganglia..)