rpmstrap is a tool for bootstrapping a basic RPM-based system. It is inspired by debootstrap, and allows you to build chroots and basic systems from RPM sources.
At present rpmstrap can build basic Fedora Core 2, Fedora Core 3, Fedora Core 4, Yellowdog 4, CentOS 3, CentOS 4, Mandriva and Scientific Linux systems. It also has support for custom RPM-based systems managed by PDK.