Also razor from emc/puppet. IMO a large scale cobbler config takes a bunch of work to get right. the provisioning and host management space is just starting to catch on to APIs and SOA. You're going to spend lots of time rolling your own apis, libs, services, and integration.
Ubuntu Orchestra: https://launchpad.net/orchestra
Or build your own around cobbler & puppet/chef, but you're sort of reinventing the wheel at that point. Still, sometimes that's fun.