Spacewalk - OSS version of RHN Satellite
Spacewalk is an open source (GPLv2) Linux systems management solution. It is the upstream community project from which the Red Hat Network Satellite product is derived.
Spacewalk manages software content updates for Red Hat Enterprise Linux and other Linux distributions (i.e. Red Hat derived ones) such as Fedora, CentOS, and Scientific Linux, within your firewall.
Check it out at http://www.redhat.com/spacewalk/