Here is a good blog entry on how to bootstrap puppet using cobbler. The author uses VirtualBox Virtual Machines, but you can easily adapt it to a physical server.
Basically, you have a kickstarter server that runs puppetmasterd and cobbler. You customize a kickstart to install puppet and start it automatically. Once its all done with the kickstart puppet runs and takes over.
It will take some time to fine tune everything to get it the way you want it, but with this set up you can create your own private LAN, create a profile for a particular server with cobbler, plug it in to the private LAN, boot and go watch a movie while your server is automatically built ;)